Abstract
The discovery of three outstanding Achaemenid buildings in Borazdjan Plain territory, such as “Charkhab”, “Sang-Siyah” and “Bardak-Siyah”, unveiled a new domain in the archaeological study of the Persian Gulf hinterlands and in the Achaemenid era. Excavation in the surrounding areas of these three buildings in two courses in the years of the decades 1350s and 1380s, led to the expsition of their different parts and architectural details. The presence of remarkable Achaemenid architectural elements including the central columned hall, lateral pillared porches and stone column pedestals, as well as the locality situations of the palaces on the plain and peripheral areas of the permanent “Dalaki” and “Shapur” and the seasonal “Ardu”rivers, made new theories possible about the quality and the reason of choosing the location and the erection of a government edifice in the Achaemenid era, while putting forward some general questions about the spatial structure of each palace. Because of the roughcast excavations, our information about the spatial extent of the unearthed collections is quite incomplete. In “Charkhab” site, for being in the vicinity of the seasonal “Ardu” river, there has been more than 1.5 meters of sedimentation which makes it difficult to access Achaemenid findings. So we decided to use new archaeological methods especially archeo-geophysical survey to study around the site and then continue the excavation around the palace according to the results obtained. So, in the first step, the western and north-western fronts with the extent of 13 hectares were surveyed archeo-geophysically using a magnetometric method and according to the outputs and the final produced map and the scatteration of exposed anomalies, some locations were determined for trenches and excavation. According to the maps obtained through magnetometry, some trenches were selected in zones where the abundance of anomalies was evident. In total, two trenches CH II and CH III, each with the dimension of 10×10 were excavated, while most findings were obtained from an Achaemenid leyer in trench CH III in the depth of 153 cm, where items such as baked bricks with the dimension 32×32×8 with bitumen mortar similar to those of Charkhab Palace, gate-pivot stones and pillar foundations worked with raw stone, pieces of cream colored pedestal stones and the most important of all, pieces of cornoture with horizontal strings similar to that of “Bardak-Siyah” Palace and  the specific palace of Cyrus at Pasargadae, can be mentioned
Keywords: Borazjan, Charkhab Palace, Archaeogeophysical Survey, Magnetometry, Excavation of Charkhab Site.

Introduction
Describing the importance of the Persian Gulf and its geopolitical role in the Achaemenid period, Herodotus describes the actions of “Scyllax Cariandi” and the order of Darius II to identify a sea route from the Indus River in India to Egypt, which was used by Indians and Iranians (Herodoutus, 1828: 289). 
In addition, other well-known historians and geographers of the early Christian centuries, such as Strabo, Arian, and Ptolemy, mentioned the Persian Gulf with titles such as “Persicon Kitas” and “Sinus Persicus”. 
The commercial prosperity of its shores is described in interaction with the West and the East. (Bayat, 1988: 28). 
Generally speaking, it can be inferred that the northern shores of the Persian Gulf inspecial, were of great importance during the Achaemenid period and later, and the construction of magnificent architectural works and government landmarks have not been unexpected.
The discovery of the remains of three outstanding Achaemenid landmarks in Borazjan plain titled “Charkhab”, “Sang-e Siah” and “Bardak-Siah”, opened a new chapter in the archaeological studies of the Persian Gulf and the Achaemenid history as well.
Excavation of these buildings during two seasons in the 1350s and 1380s, led to the discovery of various sections and their architectural components. 
Considering the presence of prominent elements of Achaemenid architecture, including the central columned hall, the side columned porches and stone pillars, along with the location of these palaces in the plains and the banks of Dalki and Shapur rivers and the seasonal Ardo valley, it has been tried to provide a definitive answer to existing questions and hypotheses based on current studies in this article. 
Asking general questions about the spatial structure of each of these palaces, provided new insights into how and why to choose a location and build a government building during the Achaemenid period. 
An important question in this field is whether these palaces were only used as summer accommodation facilities or they have been used as government seats.
Hypotheses in this study, basically suggest that the development of maritime trade, offshore communication routes, as well as suitable environmental structures and facilities, have led to the Achaemenid settlements in Borazjan plain. 
Achaemenid palaces discovered in Borazjan plain are part of the urban structures in that period. Some Achaemenid relics discovered, such as the Charkhab Palace, might have been left incomplete due to improper site selection and unsuitable location.
Architectural structures and spatial analyzes of the sites discovered in the Borazjan plain, are probably modeled on the architecture of the earlier Achaemenid culture in Pasargadae.
Studies of the surroundings of these sites show that there are other spaces related to the palaces. Based on geophysical studies as well as archaeological surveys around the sites, it can be imagined that these palaces were a collection. Further information on this subject, needs further archeological excavations and research.
One of the most important Achaemenid buildings on the northern hinterlands of the Persian Gulf is Charkhab Palace, which was accidentally discovered in 1350, during the bulldozing operations of water transfer pipeline from Borazjan to Bushehr, through the date palm groves on the western suburb outskirts of Borazjan and in the so-called “Charkhab area”.  
After preliminary investigations and the similarity of the discovered structure with the stone columns used in Pasargadae, it was decided to explore the place of discovery. The result of this excavation led to the appearance of different parts of the remains of a magnificent Achaemenid building (Sarfaraz, 1350 and 1351; Ebrahimi, 1391). Simultaneously with the excavation of Charkhab site and following the public reports that similar relics were found close a nearby village called Jatut / Jatal; Sarfaraz was able to discover another building on the banks of Dalaki River called Sang-e Siyah, about nine kilometers north of Charkhab. 
This site was excavated in 1977 by Ismail (Ehsan) Yaghmaei (Yaghmaei, 2005: 9-11; 2018: 191-196; Ebrahimi, 2012). 
During the exploration of the Sang-e Siyah remains and in the surrounding areas and palm groves, the excavations led to the discovery of another building called “Bardak Siyah” which means “the black stone”, among the palm groves of Dorudgah village. 
Yaghmaei explored the building and continued his excavations during the winter and the spring of 1978 (Yaghmaei, 2005; 1397; Ebrahimi, 2012). 
In the 2001s, with the resumption of archeological activities in Bushehr province, the Charkhab building, which had been buried under the flood deposits after the first exploration period, was excavated again by Sarfaraz in five consecutive seasons. 
In addition to the sections that were appeared earlier, some other new parts of the building became visible again. (Sarfaraz, 2001; 2003; 2004; 2005; 2006).
Due to unfinished excavations, our knowledge of the spatial extent of these collections is very limited. 
In the Charkhab area, the settled sediments are more than 1.5 meters high, due to its proximity to the Ardo seasonal river. This has made it difficult to obtain necessary findings from the Achaemenid period.
The study of archeogeophysics today, plays a crucial role in identifying the points and structures of ancient layers.
Using this methodology, saves time and also achieves the desired results much faster, much easier and much more accurately.
Therefore, we decided to use these new archeological methods, especially archaeogeophysical surveys, to conduct research around this area, and based on the results of these studies, to continue exploring around the palace.
Therefore, in the first place, the western and northwestern fronts of the palace, with an area of 13 hectares, were examined by magnetometric archeogeophysics, which revealed the dispersion of anomalies according to the output and finalized maps, and places for trenches and excavations were determined.
According to magnetic output maps, trenches were selected in areas where the abundance of anomalies was apparent.
Totally, two trenches ChII and ChIII with dimensions of 10 x 10 were excavated and most findings were obtained in trench ChIII at a depth of 153 cm and in an Achaemenid layer. 
In the cultural findings of the recent excavation in Charkhab, paddy parts of the columns with cream-colored strings are important.
Examples found in Bardak Siyah and Sang-e Siyah, are also comparable to the example of the private palace of Cyrus the Great in Pasargadae.
These paddy parts are quite different from the paddy parts obtained in Charkhab Palace (ChI), which are round and black without any carvings.
It seems that this collection (ChIII) is similar in architectural elements to those of Bardak Siyah and Sang-e Siyah palaces and those of the private palace of Cyrus the Great in Pasargadae.
The cream-colored base stone of the gateway as well as the foundations of the columns found in the ChIII trench are similar to those of Charkhab(ChI) and Bardak Siyah palaces.
The bricks obtained with  the dimensions of 33 x 33 x 8 cm and bitumen mortar in this trench are comparable to those found in the palaces discovered in Borazjan.
Given the architectural elements obtained, it is possible that this complex had been built earlier than the Charkhab Palace (ChI) itself.
Undoubtedly, more studies and more extensive research are needed to answer all the hypotheses and questions.

Abstract
According to historical and archaeological sources, the ancient city of Esfarayen was one of the important settlement centers of the Islamic era. During its existence and prosperity, this city was a link between the two famous and big cities of Nishapur and Jurjan, but from the end of the Safavid period onwards, due to various reasons, it declined and its inhabitants gradually moved to the new city. So far, parts of the ancient city of Esfarayen have been excavated by archaeologists during several different seasons. In the meantime, choosing a suitable place for archaeological excavations in this area has always been one of the most important issues for its explorers, because due to the limitation of financial resources and the large area of the area, it was necessary to determine suitable places for excavation in advance. so that its archaeological exploration can be done with more certainty. For this purpose, at the beginning of the third season of excavations, six hectares of the city were investigated with the help of magnetometric method. Then, based on the results of magnetometry, the excavations of this season were carried out. According to these explanations, the main goal of the current research is to present the results of magnetometry and compare it with the findings of the archaeological exploration of the ancient city of Esfarayen. In the current research, the descriptive-analytical method has been used using the results of field and library studies. As a result of these studies, many evidences of industrial activities were identified in the site, including architectural remains of a pottery kiln and many evidences of pottery production, which are important in the archaeological studies of the Islamic era.
Keywords: Magnetometry, The Ancient city of Esfarayen (Balqis), Esfarayen.

Introduction
The ancient city of Esfarayen, which today is known as the city of Belqis, is located in a vast plain, three kilometers southwest of Esfarayen, with an area of nearly 200 hectares. Currently, this city consists of different parts such as Arg, Sharistan, Rabz, Hesar and Khandaq. According to the documents obtained in the archaeological excavations, the city of Balqis had a settlement from the first centuries of the Islamic era to the beginning of the Qajar period (Vahdati and Nik-Govtar, 2016: 98). Due to the importance of this city in the past, several seasons of archaeological excavations have been carried out in it (Vahdati, 2016, Vahdati and Nik-Govtar, 2018 A and B, Farjami and Sotoudeh, 2019). But Balqis has a large area and the excavations that have been carried out so far do not even cover a small part of the city. For this reason, it was necessary to use remote sensing methods to identify at least a significant part of the city’s landscape and buried bodies. One of these methods, which is considered one of the branches of geophysics, is magnetometry. According to these cases, in 2009, and with the aim of identifying part of the layers buried under the soil and choosing better places for exploration, first a part of the area was surveyed for magnetometry (Aminpour, 2010). In this investigation, about six hectares of the area in a place called Tepe-Minar and also the northern part around the citadel in the southwest side of the city were surveyed by geomagnetism. By carrying out this investigation, results were obtained, based on which the third season of archaeological excavations of the site was carried out. According to the aforementioned, the main purpose of the current research is to investigate and analyze the results of the magnetometric survey of the area and the exploration that was carried out based on it. The most important question that we are trying to answer in this research is to determine the effect of the magnetometric method on choosing a better place for the purposeful exploration of the Balqis area. The method and approach of the current research is descriptive-analytical, and the method of gathering information is based on field studies from magnetometry and archeological excavations of the site, as well as library studies.

Discussion
A- The area known as Tepe Manar The results of magnetometry survey: This section included 36 grids of 10 x 10 meters. In some parts of this section, confused and jumbled magnetic anomalies were recorded, which probably indicate the transformation and destruction of its subsurface artifacts. But in other parts, the magnetic gradient anomaly map showed evidence of architectural structures and other buried ancient phenomena. Accordingly, in the part marked with the letter F, anomalies were revealed that could be related to heated masses such as brick structures or terracotta masses. The results of archaeological excavations: In order to measure the investigated parts of Tepe Manar with magnetometric method, three test boreholes were dug in the discussed area. In the first borehole, all the piles of clay and ash were encountered. In the second borehole, layers were identified, the surface and subsurface layers are sand, sand and soil, respectively, and there is a mixture of ash and soil in the lower layers. Inside the texture of soil and ash, a large amount of welding furnace and pottery was obtained. Borehole No. 3 also did not find any architectural works and only a pile of clay and ash was identified in a hole. B- The north-eastern area of the citadel the results of the magnetometric survey: In the magnetometric survey of this part of the city, several anomalies were identified. In this range, anomalies have been revealed in the form of light-colored extensions and in some cases perpendicular to each other, which can be related to the buried clay architectural structure. The results of archaeological excavations: In the scope of the second part of the geophysical survey, three boreholes and trenches were opened and explored. Borehole number one hit a pile of glazed pottery from the 6th century AH. It seemed that there was a pottery workshop around this place, because most of these pots were covered by the wastes from the pottery activity. For this purpose, a trench was excavated near borehole 1, measuring 6 x 6 meters. After removing the surface layer, a pile of pottery shards and pottery kiln debris was encountered, which were scattered on the surface of the trench at different depths. For this purpose, another borehole with dimensions of 2 x 2 meters was created at a distance in the southern part of trench 2, and after removing the surface layers at a depth of 30 cm, the remains of a pottery kiln were identified. The reason for the large amount of strong magnetic anomalies in this area is the presence of many pottery pits in this area, in addition to the pottery kiln. The date that can be determined based on the pottery obtained from this kiln is the second half of the 12th century A.D.

Conclusion
Today, in the world, magnetometry is widely used by archaeologists to identify architectural structures and buried structures. By using these methods, it is possible to examine and study many parts of an ancient site without destruction in a limited time. For this reason, in the archeology project of the old city of Esfarayen, the magnetometric method was also used during a period. Because not only the area was large, but also the limitation of resources prevented it from being able to explore a large part of it. About six hectares of the area were studied in the magnetometric survey of the area, which was carried out with the Fluxgate device. After investigating and preparing the related map, anomalies were observed in some parts of the map, which were probably related to industrial activities. Based on these anomalies, six boreholes and trenches were dug in two parts of the area to measure the results of the magnetometric survey. In almost all boreholes and trenches obtained from the excavation, evidences of industrial activities such as pottery production or pits of potter’s pits were identified. The existence of these convincing evidences is a clear proof of the magnetometric anomalies of the area. In a trench, very clear evidence of an Islamic era pottery kiln was found, around which there were several waste places. Considering these cases, it can be said that the results of the archaeological excavations of this site are a confirmation of its magnetometry project. If these studies continue and boreholes or trenches are created in other parts, we can gain more knowledge about the different spaces of the ancient city of Esfarayen.