An Investigation of Settlement and Population Distribution Pattern in Kuhdasht Plain During the Bronze Age

Abstract
The southern region of Kuhdasht is situated in the western part of Luristan Province, on the periphery of the Central Zagros in Iran. It is the second largest plain in the province, following the Sialakhor Plain. This area is bordered by Khuzestan to the south, parts of Ilam to the west, and Kermanshah Province to the north. Through archaeological investigations and the analysis of cultural artifacts and settlement patterns, we can expand our understanding of the internal and regional connections within the area, as well as the development of local cultures during the Bronze Age. The methods utilized for this research involved a combination of library research, field investigations, and the interpretation of surface findings. ArcGIS was used to analyze the settlement patterns of the plain during the Bronze Age. Locational information of settlements was recorded using GPS devices, maps were geo-referenced, and necessary outputs were obtained to estimate population distribution and biological density. The archaeological investigations revealed human presence from prehistoric to historical and Islamic eras. During the Old Bronze Age, three sites were documented in the plain, while the Middle Bronze Age consisted of three sites and one cemetery. Furthermore, the Late Bronze Age included eleven sites and one cemetery. Factors such as distance to water sources, appropriate sediments, proximity to communication routes, slope, and elevation of the plain, and the presence of fertile pastures have played a crucial role in the establishment of settlements in the South Kuhdasht Plain. The small size of the sites suggests that the inhabitants of the plain were likely cattle herders and seasonal farmers during the period under study.
Keywords: South Kuhdasht, Population, Nomads, Agriculture.
Introduction
Kohdasht is situated in the western part of Luristan Province, on the edges of the central Zagros region. The estimation of population distribution in ancient sites and regional populations relies on two types of data: 1. Archaeological data: This encompasses various elements such as ancient sites, burial grounds, remnants of human societies including pottery, architectural evidence, and other artifacts. These materials have been preserved over centuries and millennia, providing valuable insights into human habitats in a particular area. 2. The spatial distribution of cultural materials and associated behaviors exhibit meaningful patterns. Hence, ethnoarchaeology serves as a link between archaeological findings and descriptive and explanatory hypotheses. This connection was established in the 1970s when archaeologists recognized the need to formulate questions and methods that could guide ethnographers and provide information relevant to archaeological inquiries. 
This research focuses on the study of Kuhdasht, a relatively underdeveloped area in Luristan Province. The study aims to answer two questions as follows: 1. What factors affected the population distribution in South Kuhdasht during the Bronze Age? 2. How the populations in Southern Kuhdasht were distributed during the Bronze Age? The hypotheses put forward in this study are as follows: Firstly, the presence of human populations in the Kuhdasht Plain can be attributed to the favorable environmental conditions, more than anything else. Secondly, considering the limited environmental changes during the Bronze Age, it is probable that human factors played a significant role in demographic changes.
Research Method
The research employed both library study and field research, utilizing an analytical-descriptive approach. The data collection method involved a combination of using library sources and conducting field visits, while the data analysis method employed a qualitative approach. To analyze settlements and create maps, the researchers utilized ArcGIS. Additionally, ArcMap was utilized to analyze the collected locational information (recorded by GPS device), georeference maps and images, and generate necessary outputs such as catchment and DEM maps for the studied areas. Furthermore, formulas 1 and 2 mentioned in the article were utilized to estimate population and biological density in this research.

Discussion
The field activity resulted in the documentation of over 70 archaeological sites, encompassing various types such as settlements, castles, mounds, cemeteries, and other remnants of the past. Through the analysis of cultural artifacts, particularly the abundance of pottery fragments, the relative chronology spans from prehistoric times to the historical and Islamic periods. Within the Bronze Age, a total of fifteen archaeological sites have been identified, with three belonging to the Old Bronze Age and one cemetery and three settlements attributed to the Middle Bronze Age. Furthermore, eleven sites are associated with the Late Bronze Age. The disagreement in the total number of sites is due to the fact that certain sites were utilized continuously during both the Middle and Late Bronze Ages.
The factors affecting the analysis and interpretation of the population distributions and settlement patterns in South Kuhdasht Plain can generally be investigated in two categories:
- Environmental factors, including water sources, altitude, slope, land use, and vegetation.
- Anthropogenic factors, including communication routes, villages, and the surface area of the sites.
The human settlement during the Bronze Age in the studied area heavily relied on rivers, springs, and aqueducts as the main water resources. These resources played a crucial role in supporting the population. The KUhdasht Plain, situated at an average altitude of 1200 meters above sea level, is a flat plain surrounded by mountains. The landuse database mentions various types of vegetation cover in the highlands, including rainfed lands, semi-dense forest, open forest, and pastures (both dense and scattered). When comparing the population, it is evident that there was a relatively stable population during the Early and Middle Bronze Ages. However, there was a significant rise in population during the Late Bronze Age, which can be attributed to the favorable environmental conditions that led to an increase in the population during this period.
Conclusion
It is likely that population changes in the Kuhdasht Plain during the Bronze Age were influenced by human factors, as there were no significant environmental changes during this time. Limited field studies and a lack of extensive excavations in the Bronze Age sites of the Southern Kuhdasht Plain have made it challenging to determine the exact human factors involved in population and site distribution patterns. During the Bronze Age, there were archaeological sites in the plain with considerable size. The Old Bronze Age witnessed a decline in the number of archaeological sites compared to earlier periods, whereas the Late Bronze Age saw an increase in the number of sites.
The ArcGIS outputs in this research provide reference maps based on the geographical coordinates of the sites. These maps reveal that there is no specific dominant factor to determine settlement patterns and population distribution in the study area. However, the way of life in this region, which revolves around livestock raising and agriculture, is heavily reliant on water resources. This lifestyle has influenced the arrangement of the identified archaeological localities. During the Bronze Age in the southern Kuhdasht plain, it appears that the people benefited from a lifestyle that involved both sedentary and semi-sedentary practices. Despite benefiting from suitable conditions in terms of gentle slope and good-quality soils in the middle part of the plain, the settlements were primarily established near the edges of the plain in the piedmont slopes, implying a focus on animal husbandry rather than agriculture. The ideal height range of 1000 to 1500 meters above sea level seemed to suit the needs of livestock and agriculture in this region.