Abstract
Archaeological surveys have a long history, nearly seventy years, in the Upper Khuzestan plain. Despite the abundance of prehistoric sites, the number of identified Initial Village period settlements is very limited yet. Looking at the encountering history of Initial Village period settlements shows almost all of them were discovered accidentally. Besides the problem of alluvial accumulation, which is a considerable factor, there are several other reasons that affect the visibility of low and early settlements. First of all, villages in this period were obviously small and structures were built mainly using pisé and mud bricks; so buildings were less durable compared to later periods (Early, Middle, and Late Susiana). Secondly, later occupations almost covered up the whole area of early settlements. Hundreds of later sites established in the places that was favorable for earlier settlements. Consequently, at least two main reasons we infer affecting early sites in the Upper Khuzestan Plain not to be found easily are: little attention to the dynamic character of natural alluviation and deposition in the landscape of the region and incompetent field methods. These factors have prevented us to gain a full understanding of the quantity and quality of early settlements in this region. Here, by considering two factors of topography and older flood plains, an early assessment of the concentration of such early settlements in the area between the Shur and Ojirub Rivers is achieved. Boneh Rahimeh is a site that was previously merely recognized as a prehistoric site but not an Initial Village period settlement. In the present study the site is introduced as a potential pair for the Formative and Archaic Susiana site of Chogha Bonut. 
Keywords: Initial Village Period, Upper Khuzestan Plain, Dynamic natural landscape, Boneh Rahimeh.

Introduction
Archaeological surveys by the late R. Adams in the area between the Karkheh and Karun Rivers in the Upper Khuzestan Plain revealed patterns of prehistoric settlements for the first time (Adams 1962). Almost eight years later, Frank Hole conducted a survey in the same area to re-evaluate prehistoric settlements (Hole 1968). These two surveys were conducted when the existence of early phases of prehistory in the Upper Khuzestan plain was still unrecognized. In the meantime, however, in the small plain of Deh Luran, F. Hole and his collogues had introduced Ali Kosh as an early settlement in that area (Hole et.al. 1969). 
In the third season of excavations in Chogha Mish (KS0001), Archaic Susiana pottery was discovered for the first time in trenches 21 and 25 in the deepest gully of the eastern mound of the site. In addition to Archaic Susiana pottery, Trench 25 contained a new type of architecture in which long mud bricks were used (Delougaz and Kantor 1996: 4-5), then Boneh Fazel Ali (KS0002) was identified as another Archaic Susiana/Initial Village period settlement. Discovery of these remains at the latter site was a total chance; rodents’ activities had caused Archaic Susiana/Initial Village potteries to become visible (Kantor 1976). 
During leveling activities of low mounds to the south of Andimeshk, H. Wright found prehistoric pottery in the debris removed by bulldozers. Subsequently, F. Hole started excavations in this leveled area, where became known as Tulai/Tuleii (KS0372) (Hole 1974).
Again, similar developmental activities to the south of Dezful led to the identification of the already damaged and rather small site of Chogha Bonut (KS0109) by Chogha Mish excavation team. On the basis of evidence similar to those revealed in Chogha Mish and Boneh Fazel Ali, Kantor conducted some excavations in the site. Hence, Chogha Bonut was the fourth Archaic Susiana/Initial Village period settlement in the Upper Khuzestan Plain (Alizadeh 2003: XXXi).
During his epidemiological studies in the Dez irrigation Pilot area, F. G. L. Gremliza (1959-1960/1) (Gremliza 1962) collected a large number of prehistoric painted potteries from archaeological sites. Thirty years later A. Alizadeh studied and published Gremliza’s collection (Alizadeh 1992). Alizadeh’s expertise in typology of Khuzestan prehistoric pottery and in particular Archaic Susiana/Initial Village period caused Gremliza’s collection to become a reliable source for comparative studies. There is some sporadic evidence among Gremliza’s survey material that points to early settlements in the area near the Shur and Ojirub Rivers (Alizadeh 1992: 93-95; 100-105, fig.36. V; fig.37. K; fig.38.I).
It is well known that a considerable amount of later cultural remains as well as sediments cover earlier prehistoric settlements in the alluvial plains such as Khuzestan. Hence naturally early small and low occupations are buried and invisible, which makes their recognition a challenging task for archaeologists. Based on geomorphic studies conducted in the Khuzestan plain, it is clear that the sedimentation regimes were not uniform in all areas at the Upper Khuzestan plain. The Ojirub River basin area in particular, where the density of prehistoric sites is higher, bears recorded traces of old alluvium while younger sediments are recorded in the surrounding areas (Map 3). 
Like Boneh Fazel Ali, rodents’ activities led the evidence of early occupations to become visible in Boneh Rahimeh (KS0040). To the southwest of the site and around rodents’ holes, a considerable number of Archaic Susiana/Initial Village period pottery was discovered (Fig. 4), while only Late Middle Susiana and Susa II pottery was visible on the surface. A bullet core – characteristic of Aceramic Neolithic in Khuzestan- was also found in the southwestern slope of the site (currently under cultivation) (Fig. 5).

Conclusion
As stated, almost all Initial Village period settlements in the Upper Khuzestan plain were discovered by chance. In addition to Chogha Mish, Boneh Fazel Ali, Chogha Bonut and Tepe Tulai/Tuleii, where archaeological excavations led to identification of Initial Village period in these sites, evidence from previous surveys and recent investigations have increased the number of Initial Village period settlements of the Upper Khuzestan plain from 5 to 11 sites.
The dynamic nature of geographical features is considered as one of the main factors in the invisibility of earlier occupations in the alluvial plain of Khuzestan. Shifts in the course of major rivers as well as their effluents have caused fluctuations in the nature and rate of sedimentation. This, in turn, has led to form different topographic features in the region. On the other hand, the environmental potential of the region has caused the growth of later occupations, which have hidden earlier phases of settlement. Hence, almost all Initial Village period occupations are buried beneath layers of sequential occupations of later periods. 
To sum up, it seems evaluating the number and character in regards early occupations in the Upper Khuzestan plain requires updated and practical field methods. If our present knowledge about the earliest phases of occupation in Khuzestan plain was so far based on accidental revealing of lower layers of settlements by bulldozers or rodents’ activities, it is now time for applying new methods such as remote sensing techniques, studying geographical landscapes and factors affecting geographical dynamics of the region as well as archaeological intensive surface surveys in order to yield impressive results about Initial Village period in the Upper Khuzestan plain.

Abstract
The interaction of cultures in prehistoric Iran has always been one of the most important and complex topics in Iranian archeology. Such connections in different regions of Iran show the relationships of cultures and their effects on each other. During the fifth and fourth millennia, these connections became more extensive and significant. During this period in the South Zagros region, between Fars, Chaharmahal and Bakhtiari (Bakhtiari region) and Khuzestan regions, close cultural ties were formed, which are more than anything else reflected in the pottery collections of Bakhtiari region. Alain Zagarel in his studies in different parts of Bakhtiari region points out that during this period, this region has received many cultural influences from Fars and Khuzestan regions. In this article, the cultural relations that took place during the chalcolithic Age in the Early / Middle / Late Shushan period of Khuzestan, the Early, Middle and Late Persian periods, as well as in the phases of Alexandria, Chelehgah, Afghan, R1, Lapoei, Shahrak and Borjoui and S17 in Bakhtiari region have been formed, discussed and tried to answer the question of whether there were cultural connections between these areas during the chalcolithic Age or not? According to the studies, it seems that there were cultural connections between these areas during this period. The point that should be mentioned here is that in this study, the cultural influences of Fars and Khuzestan regions on Chaharmahal and Bakhtiari have been considered. The effects of these cultures on different parts of Bakhtiari region are not the same, so that the northern regions of this province during this period were influenced by the cultures of Khuzestan region and southern regions, especially Lordegan city during this period were influenced by the cultures of Fars region.
Keywords: Interaction, chalcolithic, Bakhtiari, Fars, Khuzestan.

Introduction
One of the most important field works done in Bakhtiari region is the activities of Allen Zagarel and Hassan Rezvani during the years 1390-1389. The two main plains of Bakhtiari region, namely Khanmirza, are located 180 km south to southwest of Isfahan, at an altitude of 1800 meters and Shahrekord at an altitude of 2100 meters. Both plains are very fertile pastures, but due to their height, lack of surface water and good soil, they are not suitable for agriculture (Hool, 1390: 132). The sites identified in these areas provide useful information from the pastoral pattern of the pre-pottery period. We are indicating a period of prosperity in the Bakhtiari region. Based on these activities, the question that arises here is whether there was a connection between the Bakhtiari region with Persia and Khuzestan during the Copper and Stone Age? It can be said that the initial study of copper and stone period pottery shows the relationship and close proximity of regional pottery with copper and stone period pottery in Fars (Bakun A and B) And Khuzestan (Middle and New Shushan). However, it seems that the copper and stone pottery of the lords is more similar to the prehistoric pottery of Persia (Bakun A, B and Lepui).

Materials and Methods
Cultural interactions are one of the most important and complex issues in archaeology. In this research, we first tried to study all the sources in this field well, and the pottery related to each region was carefully examined and matched with each other so that we could provide a correct and accurate comparison. Among the important sources that were used in this regard were the reports of excavations, investigations and research activities that took place in these areas during the copper and stone ages. For correct understanding and accurate analysis of the data, it was tried to use the latest archaeological activities and also the latest scientific results published in these areas.

Article Text
The pottery collection of Bakhtiari region provides us with very good information about the Copper and Stone Age, through which the connection between this region and Fars and Khuzestan can be determined. Data from all three phases of the Copper and Stone Age have been found in the Bakhtiari region. Among these, we can refer to the interregional interactions of other regions of Bakhtiari region such as Dashte Farsan with Khuzestan and Fars, and although this has been the case in previous periods(Neolithic), as the evidence shows They show that this trend has significantly increased in the Copper and Stone Age. Currently, studies show that this region is very similar to Fars and Khuzestan. Currently, studies show that this region is very similar to Fars and Khuzestan.A noteworthy point about the settlements of the copper and stone period of Farsan plain is that in this period the southern areas of Farsan plain are very similar to Bacon pottery in Persia, while the pottery of the northern half of this plain is closely similar. They have new Middle Shushan pottery.

Discussion
Based on the conducted research, it can be said that the residents of Bakhtiari region were influenced by the residents of Fars and Khuzestan during the copper and stone ages. Considering that most of the settlements in this area belong to nomads, it can be said that this area was a bridge of communication between these areas during the copper and stone ages. The presence of pottery similar to the cultural materials of the late Neolithic and copper and stone of Fars and Khuzestan indicates the strong connection between the Fars plain and the mentioned areas, and one of the important reasons for this strong connection is the migration of nomads in the Fars plain and other highlands of Bakhtiari to these areas. The identified sites of this period, which were mainly in the form of temporary camps, also prove this claim.

Conclusion
In the Copper and Stone Age, we are faced with the dramatic emergence of yards in the Lordegan area. During this time, communication between the inhabitants of Lordegan and Fars and Khuzestan has increased. The reason for this claim is the collection of pottery that exists in this area. Another reason to prove this claim is the laboratory studies that have been done on the Lepui pottery of Chaharmahal and Bakhtiari province with Fars province. Based on the researches, it can be said that the inhabitants of Bakhtiari region have been influenced by the inhabitants of Fars and Khuzestan during the Copper and Stone Age. Given that most of the settlements in this area belong to the nomads, it can be said that this area has been a bridge between these areas during the Copper and Stone Age. Khosrozadeh also points out that the presence of pottery similar to late Neolithic cultural materials and copper and stone of Fars and Khuzestan indicates the strong connection of Farsan plain with the mentioned areas and one of the important reasons for this strong connection is nomadic migration in Fars plain and other heights. Bakhtiari knows of these areas, as the sites identified during this period, which were mostly temporary camps, also support this claim.

Abstract
the beaches and hinterland of the Persian Gulf are a large part of southern Iran, which has been of interest throughout history, and many settlements have been formed in thispart of iran. This semi-closed sea has a great value in terms of natural and economic situation and military and political situation Just as the economic and social life of Mesopotamia depends on its two waterways, the Tigris and the Euphrates, and just as the Nile River plays the main and key role in the history of Egypt, in the same way the Persian Sea can be considered an important and vital bottleneck of history and civilization and Iran’s economy. Over thousands of years, this azure and fertile sea has opened its arms to   Iranians and other neighboring nations like a table full of blessings, so that the residents of its shores can benefit from its diverse reserves. The present research has focused on the introduction of pottery objects known as Gopal, which are found in abundance in the southern part of Iran, especially in the beaches and hinterland of the Persian Gulf. In this research, two library methods and field visits to some areas of the studied area have been used to collect information. The main questions of the present research are: To what period of time can the Gopals be dated? What is the use of Gopal? In what areas are the Gopals distributed? In addition to introducing Gopals and examining their technical features, the use and relative dating of these objects are discussed and the distribution map of these objects in the plateau of Iran is presented.
Keywords: Gopal, Persian Gulf, Iranian Plateau, Khuzestan, Bushehr, Hormozgan.

Introduction
As a historical and strategic waterway, the Persian Gulf has always been the focus of rulers and throughout history, it has been the place of passage for the ships of Eastern and Western civilizations. The coast of the Pars Gulf is a suitable habitat for the settlement and establishment of human societies. In recent years, as a result of the archaeological surveys of the beaches and hinterland of the Pars Gulf, many prehistoric, historical and Islamic sites and hills have been identified. Among these, a number of ancient sites and mounds of clay objects have been found, which are called Gopal. The present research has studied these objects that are scattered on the banks and back banks of Pars Gulf.
Research questions: In this research, the most important questions include: 1- In what regions is the range of distribution of clay objects known as Gopal? 2- Are Gopals produced in the northern part of the Persian Sea? 3- Do these objects have different types in terms of appearance? 4- Gopals belong to what period of time? 5- What is the use of Gopal?

Gopal classification
Clay objects known as Gopal are clay cylinders whose height varies between 15 and 30 cm and their weight varies between 1 and 4 kg. The upper part of the Gopals is round with a diameter of 10 to 17 cm and the lower part is saucer-shaped with a diameter of 6 to 12 cm. Their floor is rough and uneven, but they are stable to be on the ground. Williamson has introduced the Gopals with the title of base and divided them into four categories, Gavbandi type, Bushehr type, Ganaveh type and Tepe Yahya type (Williamson 1972: 100). According to technical specifications and appearance, Gopals were classified into 9 types. But since this study is mostly in the form of a library and the distribution area of Gopals has not been fully investigated in the field, it is possible that there are more and different species that are hidden from the authors of this study.

Distribution of Gopal in the Persian Gulf
The basis of the study of the distribution of Gopals is the study of survey reports, records and field studies (Table 1) that have been published and published so far, as well as the authors’ visits to a number of sites on the beaches and hinterland of the Pars Sea. The distribution map presented in this research is the beginning of a way to carry out additional studies in the field of these clay objects in the future and undoubtedly has some shortcomings (map 1). The distribution of this pottery was in the beaches and hinterland of the Persian Gulf as Louis Pelly says: they are found along the coast (Pelly 1863-1864: 44). Hertzfeld He writes: “Along the shore, under the ruins of early Islamic houses, large quantities of clay handles are found, which are called Gopals, and are introduced as flakhen, (Herzfeld 1926: 260).
The most distribution of Gopal in Behbahan city is in Zidon section. The Gopal area in the south of Omidieh belongs to the middle Islamic centuries, of this Gopal as “Clay base” (Sadeghi Rad 2018).
In Bushehr province, the distribution of these pottery objects increases significantly and they are found in abundance in almost all of the province. Gopals of different types have been reported from the grounds of Sarkho Castle, Shahzadeh Mohammad Darvishi in Shanbeh and Tasuj sections of Dashti city (Zarei 2018: 143).
In the north-west of Fars province, two samples were introduced from Tell Ahangaran and Tell Khazaneh in Noorabad Mamsani in the study of Askari Chavardi, the first sample is Gopal made of stone. In the west of Fars, in the area of Fathabad in Sarmashed of Kazeroon city, in the research of Parsa Ghasemi, broken samples of Gopal clay were reported, which are “scattered in the plowed lands” (Ghasemi 2010: 327-327).  In the southern part of Fars province, the distribution of Gopals is more and these objects have been reported from six sites. Golrokh hill is located in Chahorz district, Lamard city, (Askari Chavardi, Amiri: 2002) A small round base was found on the surface of Tape Yahya, probably from the second period (Achaemenid period). This type, which is scattered throughout the Jiroft region, can be easily distinguished from the 3D type, and it may be considered the background of the Sassanid foundations.” (Williamson 1972: 100) and in the southern part of the Persian Sea, he refers to Al-Ain in Abu Dhabi, where Bushehr-type clay foundations are scattered there (ibid.).

Examples similar to Gopal
In terms of the overall shape and appearance of the Gopals, there are similarities with objects such as decorative studs obtained from Chaghazanbil, and probably those who consider these objects to be architectural decorations because of the similarity between There were Gopals and studs (Figure 13).
The example of a fire pit (Figure 14) which Mustafavi believes is related to the Seleucid period (Mustafavi 1968: 71) or the base of fire pits made of stone or plaster from Weigal (Javari and Bagh-Sheikhi 2019), Plang-Gard (Alibeigi 2012: 201), Shian (Moradi 2009), Bandian Derghez (Rahbar: 2008), Imamzadeh Mohammad (Askari Chavardi 2010), Tell Shahid, Keshto village and Brazjan (Tawfiqian 2017) and the images of firetemple on the coins of Sasanian kings. , have general similarities with Gopal (Figure 14).
Williamson introduces a type of wooden bases that are painted and were used for Bushheri or Kuwaiti boxes, and these clay bases are the background of wooden bases (Williamson 1972).
A type of tallow burners that became very popular in the Islamic period (Wilkinson 1973) are examples similar to Gopal. Two stone objects have been found from Imamzade Abdullah in Shushtar, which Ahmad Eghtari refers to as fire pits or the base of fire pits belonging to the Parthian period. He classified them except Gopal (Eghtari 1996: 703-702). (Figure 15). Unglazed candlesticks with a similar design have also been found in Merv (Wilkinson 1973: 314) (Figure 15). In Hormozgan province, there is a type of embroidery called Shakbafi, for its weaving and production, they use a tool similar to gopal, called Choghn. A cloth is placed on it (Figure 16). The material of this mortar is sometimes wood and sometimes clay or plastic, which is actually considered a support for a pillow and a base for weaving a tape” (Mokhtari-Dehkordi, Asadi Farsani 2013: 39).

Dating and use of Gopal
Without conducting detailed experiments and extensive and methodical studies, the dating of Gopals will be relative, it is also necessary to know the use of these clay objects in the hills and areas where they are widely produced and used. Methodical archaeological excavations should be carried out. There are many theories and assumptions about the use of Gopals. Lt. Col. Lewis Pelley, says about the Gopals: “I picked up some spirally grooved cylinders of baked clay. Traditions say that these cylinders were the ones that the infidels used to use a leather strap to attack. They threw targets” (Pelly 1863-1864: 44). After pointing out Poly’s opinion and its illogicality, Haynes Gaube mentions these objects as architectural decorations and the limitations of this assumption are listed, including why they are found in Siraf but not in Khuzestan? (Gaube 1980: 384). Herzfeld believes that the use of Gopals is similar to the Assyrian clay studs, whose ends were placed in Diora (Herzfeld 1926: 260). Williamson believes that the Gopals were used as bases for holding wooden chests known as Bushheri or Kuwaiti chests, and later they were replaced by painted wooden bases (Williamson 1972: 101).
Parsa Ghasemi believes that these terracotta objects had an architectural use, similar to the columns used in the Achaemenid building of Dahane Gholaman (Ghasemi 2009: 86). Askari Chavardi mentions clay Gopals as the base of Sasanian vessels (Askari Chavardi 2012, Askari Chavardi 2018) and the type of stone that he considers as the base of the hearth (Askari Chavardi, Pots, Pitri 2013: 149-148).
During a conversation with the residents of Shahr-e Viran in Dilam city, they stated that the nomads use these pieces of clay for weaving ni-chit (Chiq or Chikh) (Figure 17), and it was believed that these tools are used for production Nothing has been used. Kamiyar Abdi believes that these clay objects have industrial use (Abdi 2007).

Conclusion
During this research, the existing Gopals were classified into 9 categories according to their appearance and technical characteristics, their exact typology requires a systematic archaeological investigation in the distribution area of Gopals in the banks. And then the beaches of the Persian Glf. The present studies showed that Gopals are mostly found in the sites related to the Sassanid and Islamic periods.
According to the terminology of Gopal or Gopal, it is not true that this pottery object has a war function, and probably only according to its appearance, they put the name of Gopal or Gopal on it. According to examples similar to Gopal used in the art of embroidery, the assumption that Gopal was probably used as a tool used in sewing or weaving industries. According to the classification done, Gopals probably had various uses. As long as the Gopals are not recovered from their context, determining any use for this clay object will be more of a hypothesis.

Abstract
Prior to L. Afshari’s fieldwork in Ramhormoz, the known Achaemenid sites from the plain only amounted to 17 in number. Yet, given factors such as favorable climate and fertile soil for agriculture, existence of important rivers such as Kupal and Sandali, proximity to such trade routes as the Susa-Persepolis royal road as well as to the two major Achaemenid capitals of Susa and Persepolis, we deemed the figure to be rather underrated, believing that there must be much more concomitant settlements in this plain. During our investigation, the sites recorded by the previous team were re-visited and new coeval sites were also identified. The survey of 2020, directed by one of the authors (L. Afshari), did not encompass the entire Ramhormoz plain. Covering only its middle part straddling the Ala River with a total area of about 53000 hectares (530 sq. k), the survey recorded 36 Achaemenid settlements. Identification of the relevant sites was based on Khuzestan’s local pottery of the Achaemenid period reported from Tape Daroughe. In this study, the impact of geographical factors such as the presence of large rivers and fertile lands on the genesis and prosperity of settlements was evaluated. The surface architectural finds are suggestive of interactions between rural and nomadic communities. Results of the surveys indicated the proximity to ancient royal roads and access to water sources and pastures to be the determining factors in the distribution pattern of Achaemenid settlements over the Ramhormoz plain. This survey program aimed to identify and locate the Achaemenid sites in the Ramhormoz plain, to examine their interrelations, to record their characteristics through sampling and observing pottery pieces, to establish a relative chronology for them based on the typology of surface pottery collections, and final to draw cross-regional typological comparisons with major sites in other parts of Iran, South Mesopotamia, and East Anatolia.
Keywords: Southwest Iran, Khuzestan, Ramhormoz Plain, Settlements, Achaemenid Period.

Introduction
The vast region of Ramhormoz stretches up to the mountain belt of Khuzestan to the north. Sitting in the eastern Khuzestan plain at an elevation above sea level of 120 m, the plain of Ramhormoz encompasses a total area of 620 sq. km. All across southwestern Iran, Ramhormoz is the region with the least archaeological investigation. Despite this paucity of work, recent studies have demonstrated the regional settlements (in both mountains and plains) to be integral to any understanding of the culture of the Achaemenid period. Geographic location of the region, the nature of settlements in the transition zone between plains and mountains, and their continuity and cultural ties with each other also furnish a pattern for grasping the Achaemenid world’s settlement policy. In addition, given its strategic location during the concerned period, the plain assumed a central role in the interactions between Iran, Mesopotamia and Anatolia. It is of great importance also because of its location on the Royal Road from Susa to Persepolis.
The southwestern region of Iran played an important role in establishing cultural, economic, and political interactions with surrounding areas such as Mesopotamia and Anatolia throughout the 1st millennium BC. The number of archaeological studies conducted in the Ramhormoz area has been quite limited. Despite the lack of archaeological information, the studies carried out in recent years have shown the significant role the cultures in the region (both the mountain and plain settlers) played in understanding the Achaemenid Culture.
The significance of the region was further revealed with the surface surveys carried out by Donald Mc Cown in the region and the excavations he conducted at Tol-e Geser (McCown, 1949, 1954). Surveys conducted by Wright and Carter in 1969 also pointed to connections between the region’s lowland and mountainous parts of southwestern Iran (Wright and Carter, 2003). Although the dimensions are different, it has been observed that the settlements share some common features with the mountainous parts of Persian geography. As a result of contemporary archaeological resources and the survey conducted under my supervision, the characteristics of the Achaemenid settlements in the Ramhormoz plain in Southwest Iran were reanalyzed. The influence of geographical factors such as the presence of large rivers and fertile lands on the formation and prosperity of the settlements and the relations between sedentary, rural, and nomadic communities were studied. Also, the transformations in the settlement system, distribution, and population differences during the Achaemenid period were revealed and subsequently / mapped.

Discussion
This survey program aimed to identify and locate the Achaemenid sites in the Ramhormoz plain, to examine their interrelations, to record their characteristics through sampling and observing pottery pieces, to establish a relative chronology for them based on the typology of surface pottery collections, and final to draw cross-regional typological comparisons with major sites in other parts of Iran, South Mesopotamia, and East Anatolia. The realization of the latter aim will have important implications for the Achaemenid archeology of southwestern Iran, altering the existing views. In light of our findings, it is possible to propose a distribution pattern for the settlements in the middle of the Ramhormoz plain as being clustered in two regions, viz. northwest and southeast, on both banks of the Ala River. The finds of primary importance from the settlements of the plain are pottery assemblages. To explore the Achaemenid pottery, they were first classified by shape, which consisted of the five groups of carinated bowls, bowls with a spherical body and a simple rim, necked jars, short-necked jars, and storage jars. This was followed by comparative studies for dating the pottery. Our observations show that the Achaemenid pottery traditions continued well into the subsequent period after the demise of the empire.
Thus, it is notable here that the materials and settlements discussed in this paper can potentially extend in date to as late as a century after the Achaemenid period. In terms of technical characteristics, the pottery splits into five groups: common, light green-slipped, red-slipped, eggshell, and painted wares.
Drawing on historical sources and archeological findings as well as the conducted studies, the villages across the plain tend to be clustered around or be related to the Susa-Persepolis trade route. The rich geography of the plain has informed the dynamics of its settlements over time. Notwithstanding the severe disturbances induced by modern settlements and agricultural and industrial activities, the identified settlement centers reveal direct or indirect link with the commercial or military routes of the Achaemenid times. In other words, their formation along the commercial routes was primarily meant to facilitate intra- and cross-regional contacts. The proximity of settlements to the royal road between Susa and Persepolis evinces the integral role the road played in the cultural interactions of the Achaemenid period. Therefore, archaeological studies directed by Esmail Yaghmai are important in detecting the remains of settlements along the royal road linking Susa to Persepolis as they reveal the characteristics of the settlement policy. 

Conclusion
With the completion of the archaeological investigation in the Ramhormoz plain and the study of the findings and data obtained from this investigation, it seems that a general understanding of the cultural remains related to the Achaemenid period and the distribution of the sites of this period can be achieved to some extent. It was thus revealed that proximity to commercial roads and access to water resources and pasture were the main determinants in the distribution model of Achaemenid settlements. Rich pastures for nomads, the potential for irrigated agriculture for settlers, and access to communication routes provided advantages for both lifestyles. Therefore, the settlement pattern is more associated with roads. When the location of the settlements and their distance to each other are examined, it is seen that the frequency of settlements on the Susa-Persepolis Royal Road is very high. Settlements are located on the road within short distances of each other, which shows that the road is a determining factor on settlements in the region due to its socio-economic advantages.
Ramhormoz plain shows that the Achaemenid settlements in this plain maintained strong intra- and cross-regional cultural and economic ties. In terms of extent, Tol-e Ishan Seyyed Shabib or Tol-e Toupi, Tape Mava, Tape Mehr Alnesa and Tape Kheyr Alnesa appear to be examples of such type of villages. With respect to the location of settlements and their distance from each other, a concentration of settlements is discernible along the Royal Rod—they are clustered along this road at close intervals. This fact indicates that routs played a decisives role in the formation of regional settlements, and that the Royal Road yielded multiple economic and political advantages. In general, it is possible to say that most of the settlements in the Ramhormoz plain lie on the riparian areas or along the Royal Road from Susa to Persepolis, and judging by the pottery collections, there clearly were close interrelations between these settlements and interactions with neighboring regions. On this very basis, one may safely surmise that a local and highly advanced pottery industry prevailed in the plain during the Achaemenid period. Cross-comparisons of the surface pottery assemblages from the Ramhormoz plain with the excavated material from sites in southwestern Iran, southern Mesopotamia and eastern Anatolia indicate the presence of early, mid- and late Achaemenid ceramics, suggesting that the Achaemenid cultural horizon continued uninterruptedly over the plain between 330‒550 BC.

Abstract
Khuzestan, a primary center of mudbrick and fired-brick architecture in ancient Iran, witnessed the evolution of vaulted construction from the Elamite to the Late Sasanian periods. Among these, arched vaults served not only as structural elements but also as a demonstration of systematic engineering practices tailored to the region’s warm and semi-humid climate. Despite the abundance of surviving monuments, no comprehensive study has analyzed their technical and structural features to uncover the underlying stability principles. This study aims to examine the structural performance and recurring patterns of stability in arched vaults of Khuzestan. Field surveys, documentation of accessible structures, analysis of 111 identified vaulted buildings, and detailed examination of 21 selected representative examples were conducted. The study focused on the interaction of materials, geometric proportions, construction technology, and human craftsmanship in achieving long-term stability. Results indicate that vault stability depended on: 1) the type and geometry of bricks, consistent mortar thickness, and interlocking strategies; 2) diverse construction techniques, including corbeling, radial arrangements, and combination methods; 3) geometric proportions such as span, rise, and vault thickness; 4) adaptation to climatic conditions; and 5) the skill and experience of the builders. This research highlights the presence of a systematic engineering logic in pre-Islamic vault construction and provides a framework for restoration, conservation, and potential adaptation in contemporary architectural practice. The findings demonstrate that these vaults were not merely empirical or accidental in design but reflect deliberate, replicable, and coherent structural strategies.
Keywords: Structural Stability, Vaulted Architecture, Arched Vaults, Pre-Islamic Iran, Khuzestan.

Introduction
Khuzestan has historically played a pivotal role in the development of vaulted architecture within ancient Iranian civilizations. Vaults represent one of the most sophisticated elements of traditional construction, combining technical mastery, material understanding, and adaptation to environmental conditions. From the Elamite through Late Sasanian periods, vaulted buildings in Khuzestan reveal an evolution in construction techniques, reflecting the accumulation of knowledge and local innovation. Arched vaults, in particular, served as primary structural and functional components in ritual, funerary, administrative, and sometimes military architecture.
The study of these vaults provides insight into the strategies employed by ancient builders to achieve stability over centuries. Stability in traditional architecture encompasses not only physical durability but also cultural, climatic, and technical resilience. Builders utilized local materials, precise geometric proportions, and structured load distribution to respond to environmental and functional challenges. Despite extensive archaeological documentation, there has been limited focus on the technical principles underpinning vault stability, particularly in arched vaults.
This research addresses this gap by systematically analyzing recurring structural features, material properties, construction technology, and geometric patterns that contributed to vault durability. The study examines both historical continuity and the adaptation of techniques over time, demonstrating that pre-Islamic vaulting practices in Khuzestan were informed by deliberate engineering logic rather than trial-and-error. Understanding these principles is critical for bridging knowledge gaps in architectural conservation, informing restoration efforts, and inspiring contemporary applications of traditional construction methods.

Discussion 
Analysis of arched vaults in Khuzestan indicates that their long-term stability resulted from a combination of material selection, construction technology, geometric design, and human skill. Key aspects include:
Materials and Mortar: Builders employed trapezoidal, square, and rectangular bricks, wider and thicker at structural bases to distribute loads effectively. Mortars, including clay, gypsum, and bitumen, were chosen according to moisture conditions, ensuring cohesion and stability.
Construction Techniques: Techniques included inclined corbeling, radial arrangements, and hybrid approaches. Temporary wooden or reed supports facilitated precise execution, while multi-layer vaults with controlled thickness enhanced overall strength. Adjacent vaults were often coordinated to reduce lateral stresses.
Geometric Proportions: Ratios between span, rise, and thickness were carefully maintained across periods. Numerical proportional systems guided vault dimensions, while precise interlocking of bricks ensured efficient load transfer.
Human Skill: Mastery in aligning bricks, controlling mortar thickness, integrating vaults with walls, and designing stress-relief features such as recesses and buttresses reflected high craftsmanship.
The historical evolution from Elamite to Sasanian periods shows gradual refinement. Early Elamite vaults utilized simple rectangular cross-sections and limited brick types, while Late Sasanian vaults displayed sophisticated high-rise arches, modular brick use, and multi-layer arrangements. These developments indicate a cumulative knowledge system that informed construction practices and responded to functional and climatic challenges.
The study highlights that stability was never accidental; rather, it emerged from repeated, rationalized engineering practices. Such findings provide an empirical basis for restoration and reconstruction, enabling the preservation of architectural integrity and informing contemporary design strategies that draw upon historical methods.

Conclusion 
This research demonstrates that arched vaults in Khuzestan were underpinned by systematic engineering principles rather than empirical trial-and-error. Stability resulted from the integrated interaction of materials, construction technology, geometric design, environmental adaptation, and craftsmanship. The study identifies: 
- Strategic use of brick types and mortar selection to optimize structural cohesion.
- Refined construction techniques, including corbeling, radial arrangements, multi-layer vaulting, and controlled thickness.
- Geometric proportionality ensuring balanced distribution of forces.
- Adaptation to climate and environmental constraints.
- High-level craftsmanship in aligning elements and controlling structural behavior.
Historical analysis reveals a continuous technological development, culminating in Late Sasanian vaults that exemplify peak structural refinement. Documenting these features provides a foundation for preservation, restoration, and potential adaptation in modern architectural practice. Future studies may compare these vaults with contemporary structures in neighboring regions or explore the influence on early Islamic architecture in southwestern Iran.
The study confirms that pre-Islamic vault construction in Khuzestan represents a coherent, replicable, and sophisticated engineering tradition, offering valuable lessons for both conservation and contemporary design.