Abstract
In the Holocene, there has been a sudden and severe climate change that has affected the process of cultural evolution, subsistence system, demographic change, and the pattern of the distribution of human settlements. Palaeoclimatological studies show that in the second half of the 7th millennium BC, during a cold and dry climatic event, with a peak of about 6200 BC, the settlement conditions, in particular in some parts of the Northern hemisphere, were significantly disturbed. After this period, the air temperature rose sharply and replaced the warm and dry climate from the beginning of the 6th millennium BC. From the second quarter of the 6th millennium BC, gradually, the amount of humidity increased and the air temperature decreased, so that from the beginning of the second half of the 6th millennium BC, more favorable climate conditions were created for agricultural activities. The early evidence of the human settlements in the North of Central Iran region mainly belongs to the beginning of the sixth millennium BC. Due to the lack of architectural evidence from the first half of the 6th millennium BC in this region, human societies were probably semi-sedentary. From about 5400 BC, sedentary-farmer settlements with architecture were established and gradually their number increased. In the early 5th millennium BC, a warm and dry climatic change caused the interregnum/collapse of the settlements in the region. Therefore, the time of the genesis and prosperity of the early settlements in the North of Central Iran was related to the climatic conditions and occurred in an appropriate climate period between two dry periods.
Keywords: The Mid-Holocene, Climate Change, 6200 BC Event, 6th Millennium BC, The North of Central Iran.

Introduction
Although human beings have the liberty in nature, the study of the cultural evolution of human societies without reference to environmental change cannot be valid. In other words, one of the main motives of cultural dynamism and evolution is interactions between humans and the environment.
The Holocene period is divided into three phases: the early Holocene (ca. 9700 - 6000 BC), the middle (ca. 6000-3000 BC) and the late (ca. 3000 BC). Abrupt climate changes, both warming and colding, which have led to drought and unfavorable environmental conditions, have repeatedly occurred since the beginning of the Holocene age and have led to cultural collapses in human societies. However, between these climatic events, we often witness the birth of a new or evolved culture.
In the cultural region of the North of Central Iran, with the exception of the Western Tepe of Sang-i Chakhmaq, no evidence has yet been found of human settlements belonging to before the sixth millennium BC (the beginning of the Middle Holocene). Due to the occurrence of the 6200 BC climatic event, which caused a severe cold-drought period for 200-400 years (in different regions), presumably, the lack of prehistoric sites has been linked to unfavorable climatic conditions in this arid and semi-arid cultural region. The results of palaeoclimatological studies, together with absolute datings, can not only be useful in more accurate chronology of ancient sites, but also they can explain the causes of population changes, settlement patterns, many of migrations and displacements of human societies, as well as changes in their diet and lifestyle. In this study, considering the climatic condition of the early Mid-Holocene, based on the palaeoclimatological studies carried out in several sites, the initial status of human settlements in the North of Central Iran region during the sixth millennium BC will be discussed.

Research Findings
In the Holocene, the air temperature and moisture significantly increased compared to the Ice Age, and the changing climate led to the emergence of the Neolithic Age and food production. However, during this period, despite the high average of the air temperature, the earth experienced severe climate changes, which affected cultural development, demographic changes, subsistence system, and the distribution pattern of human settlements. Around 6200 BC, suddenly, a very cold climate change occurred, which lasted 150 to 600 years in different regions. The occurrence of this event led to changes in the lifestyle of the Neolithic communities. The cultural region of the North of Central Iran consists of two parts: the Western part (the salt lake basin) and the Eastern part (the Western half of the central desert basin). The oldest Neolithic settlement in the Western part of the region is the Western tepe of Sang-i Chakhmaq dating back to 7200 BC to 6600 BC, but in the Eastern part, no settlements belonging to before 6100 BC have been found.
So far, a few semi-sedentary sites belonging to the first half of the 6th millennium BC in the salt lake basin have been identified. Palaeoclimatological studies show that the air temperature and humidity have suddenly increased sharply after the 6200 BC cold event. However, since the second quarter of the 6th millennium BC, the air temperature has gradually decreased. In the middle of this millennium, an abrupt warming fluctuation occurred, but from about 5400 BC, the air temperature and humidity reached an optimum level for agricultural activities. In general, the early sedentary-farmer settlements in this region belong to after 5400 BC. However, at the end of the 6th millennium BC, another climate change caused severe warm-dry conditions, in which, since the beginning of the fifth millennium BC, settlements gradually collapsed.

Conclusion
The cultural area of North Central Iran consists of two parts: West (catchment basin of Namak Lake) and East (Western half catchment basin of central desert). The first Neolithic settlement in the Western part of this region, Western mound of Sang-i Chakhmaq with dating 7200 BC to 6600 BC. In the eastern part, so far, no settlement older haven’t been found than 6100 BC. The early sedentary-farmer settlements in the cultural region of the north of central Iran, such as Yan Tepe of the Ozbeki site, Tepe Ibrahim Abad, Tepe Moein Abad, Northern Tepe of the Sialk site, Tepe Pardis and Tepe Cheshmeh Ali, have been established and developed in a 400-year period between 5400 and 5000 BC with a relatively mild and humid climate, between two severe drought periods.

Abstract
The Upper Gotvand Dam, with a 90-kilometer-long lake, is one of the largest dams in the country, and its impoundment caused the flooding of a large number of ancient sites, ancient and modern migration routes, villages, and nomadic settlements in the northeastern region of Khuzestan. Before the dam was completed, a team of archaeologists surveyed its basin in 2007. After that, in 2008, a team of archaeologists from ICHTO of Khuzestan Province excavated the Kalantar site and the Kalantar cemetery, and then in April and May 2010, salvage excavations were carried out at Kalantar 4 & 5 sites to obtain as much information as possible, which yielded significant results. Following the excavation of the Kalantar 5 site, traces of residential stone architecture, plain buff and red pottery, and turquoise blue and green glazed pottery, as well as some ground stones such as grinding stones, mortars, and pounding stones, were found. According to typological comparisons on the potteries, it was determined that they belonged to the Middle Islamic period (fifth and sixth centuries AH), and the site was inhabited during the Seljuk period. In addition, it was determined that there is a great similarity between the stone architecture of the Kalantar 4 (a Neo-Elamite site), and the Kalantar 5, and with the local architecture of the region in the present time, both in villages and in nomadic settlements. In other words, the continuity of cultural traditions over several millennia is observed in this area.
Keywords: Kalantar 5, Gotvand Dam Basin, Middle Islamic Period, Stone Architecture, Islamic Glazed Pottery.

Introduction
The Upper Gotvand Dam was built on the Karun River near the small town of Gotvand to generate electricity and irrigate downstream agricultural lands, and a wide range of intermountain valleys, numerous ancient sites, ancient and modern migration routes, villages, and nomadic settlements were submerged in the 90-kilometer-long lake behind the dam. Before the dam was impounded, two teams led by Shahram Zare and Hossein Azizi Kharanghi, respectively, surveyed the area (Azizi Kharanghi et al., 2007). Salvage excavations were conducted by Hamidreza Valipour on two sites, Kalantar 4 and 5, which were found during the surveys in the spring of 2010 (Valipour, 2010a & b). The preliminary results of the excavation of Kalantar 5 will be presented here.
The first goal of the excavation, like all salvage excavations, was to access as much information as possible. Due to the proximity of Kalantar 5 to Kalantar 4 and the similarity of its surface architectural structure with the architecture of Kalantar 4, the excavation team was faced with some questions, the most important of which were: 1- Is Kalantar 5 an extension of the Kalantar 4 settlement and can we consider them as one site? 2- Was the settlement in Kalantar 5 established after the abandonment of Kalantar 4 and as a result of the displacement of its residents? 3- Does Kalantar 5 belong to a different time than Kalantar 4? Of course, given the presence of Islamic pottery on the surface of Kalantar 5, it was assumed that this area, in addition to the Elamite period, would also contain evidence of settlement from this period. 4- Function and type of settlement in Kalantar5.

Kalantar 5
Kalantar 5 is located on a natural hill south of Kalantar village (Ab Zālu Arab) in Lali County, at N: 32˚ 13΄ 42/6˝ latitude and E: 049˚ 04΄ 55/4˝ longitude, 160 meters north of Kalantar 4 and 13 kilometers east of the Gotvand Dam. The highest point of the site is 278 meters above sea level. The Karun River, the closest major water source to the site, flows 4.5 kilometers northeast of the site; a water stream also passes through the valley to the northwest.
During the excavation, one trench was opened at the highest part of the site, measuring 10×10 meters, where the regular stone pieces and traces of walls indicated the existence of architectural spaces in this part of the site. Given the depth of the natural bedrock, it was clear before the excavation began that not much height of the walls remained.

Architecture
A total of six architectural spaces were revealed during the excavation in Trench I. Stone and mud mortar were used in all the architectural structures. The stones used in the construction of the different parts of the complex are soft limestone in small to large sizes. All the stones lack cutting polish but have an almost regular shape. Many of the stones used in the architectural structures are cubed. The walls are rectangular. The walls lack any covering, and even during the excavation in the rubble layers, no samples of mud, plaster, or lime were found. The six aforementioned spaces seem to belong to the same building because they all share walls. It is possible that the natural bedrock of the hill was used as a floor for the spaces. Stone supports were used in addition to all the main and internal load-bearing walls. The entrances were mainly created by not connecting two walls or by cutting off part of the length of a wall. Next to some walls, there are smaller annexed spaces as storage places, which were probably used to store daily necessities or food or fuel, and they lacked any entrance and were accessed from above. A pyrotechnical structure was found inside one of the spaces, about one-fifth of which remains. Since a very small part of it remains, it is difficult to distinguish its function as an oven or else. No evidence of a roof or debris was found during the excavation. Given the relatively small width of the spaces and the absence of columns, the roofs of the spaces were most likely created using parallel wooden poles and covered with mats or tree branches and mud. This reconstruction was carried out in comparison with the current situation in the village adjacent to the site. The reason for this comparison is the great similarity of the architecture obtained from the settlement spaces of the site with the architecture of the adjacent village.

Pottery
The 319 potsherds recovered from the excavation are divided into two major groups: plain and glazed. 265 sherds (83%) of the total are unglazed. Unglazed pottery can be divided into two groups: buff and red. The technology of pottery production is completely similar in terms of form, manufacturing technique, inclusion, firing, and decoration. Most of the sherds are wheel-made (96%). The inner and outer surfaces of the pottery are unpolished, and both sides of the vessels are smoothed by the wet hand method. Rarely, red wash was used to cover a handful of buff wares. The texture of buff ware is much more cohesive than that of red ware. Mineral materials such as fine to coarse sand were used as an inclusion in unglazed pottery; in one of the red potteries, the inclusion is a combination of organic and mineral materials. In general, the quality of buff-colored pottery is better than that of reds, and the number of buff sherds is much greater than that of reds. 236 sherds (74% of all pottery and 89% of unglazed pottery) are buff, and 29 sherds (9% of all pottery and 11% of unglazed pottery) are red. There are 10 sherds of pottery with incised decoration in the unglazed buff group.
54 pieces (17%) of the pottery are glazed. Except for two pieces with green glaze, the rest are turquoise blue. The pottery of this group is in the category of pottery with monochromatic glaze. Five pieces are also of the sgraffiato type with turquoise blue glaze. In terms of form, manufacturing technique, inclusion, firing, and color, these sherds are completely similar to the unglazed buff wares. The inclusion of all samples is mineral.
The reconstructed forms are the jar (44.5%), bowl (37%), and bowl (18.5%), respectively. The sherds date back to the 5th and 6th centuries AH and are dated to the Seljuk period (Karimi & Kiani, 1985; Towhidi, 2000; Kambakhshfard, 2001; Grube, 1994; Treptow, 2007).

Other Cultural Materials
In addition to pottery, other cultural materials recovered included animal remains, pounding stones, stone mortars, pivots, iron nails, iron knife, the bottom, rim, and body of transparent or opaque glass vessels in blue, yellow, and milky colors, as well as a few broken shells.

Conclusion
Kalantar 5 is a rural settlement site from the Middle Islamic period because considering the landscape of the region, the location of the site, the extent of the architectural remains, and the dispersion of cultural materials, it is unlikely that the settlement was urban. There is no connection between the sites of Kalantar 4 and 5 from a cultural and temporal perspective. An interesting point to note is the similarity of the architectural structures of this site with the architecture of Kalantar 4 and the modern village of Ab Zālū Arab and other nomadic villages and settlements in the region. With an ethnoarchaeological approach, this similarity can be considered a kind of cultural continuity in architecture. Perhaps the same environmental and subsistence conditions can be considered the reason for the construction of similar architecture over a long period.
The buildings were constructed using completely local materials, such as stone and mud. All the stones are limestone, ranging in size from small to large, and are uncut and unpolished but have a fairly regular shape, and many of the stones have been broken using chisels and hammers. It seems that the six identified spaces had both roofed and open sections. The three spaces 1, 3, and 4 were associated with activities that required separation from the residential areas; the three spaces 2, 5, and 6, which are part of the main residential complex, were probably places for resting and performing other daily activities. These three spaces are connected by some entrances.
All finds, from functional examples such as pottery, glass vessels, pounding stones, and mortars to decorative shells, indicate a normal settlement, and all of them are related to daily life activities.
The pottery of the Kalantar 5 bears no resemblance to the Kalantar 4 site. Many of them are Islamic glazed pottery, including monochrome green and turquoise blue glazes and some with incised patterns under the turquoise blue glaze. The pottery is not very diverse in terms of color, glaze, type, and theme of the patterns. These potteries date back to the fifth and sixth centuries AH and are dated to the Seljuk period. During this period, the glass industry in Iran was very prosperous (Shishehgar, 2003: 24), and glass fragments recovered from a rural settlement site confirm this.