The Hierarchyand Central Place Patterns of the Chalcolithic Sites in the Bakhtiari Highlands, Iran

Laran district with a total area of 516.28 km2 is adjacent from north with Isfahan province, from northwest and west with Kuhrang city, from east and south with Shahrekord city and southwest with Farsan city (Figure 1).The region is originally a valley with a northwest-southeast direction along with smaller sub-valleys, which have environmentally, permanent water resources including the Zayandeh-Roudbasinin the north and the southern parts of the Karunbasin and permanent and seasonalsprings, and now it is a countryside and one of the routes and roads of the migration of tribes of Bakhtiari. The altitude of the area is more than 2036 m and the subsistence of the today’s people of the region is low due to the lack of level and flat lands, herding, nomadism, permanent agriculture and aquaculture. According to the data and statistics, the average rainfall in the stations of the region for the past 19 years in March was 72.2 mm and the average of the lowest rainfall in 19 years was in August with an average of 0.7 mm. The coldest month is also in Novemberand December with an average temperature of -24 °C and the highest recorded temperature in July and August with an average of 46 °C [1-8].


Theoretical foundations of Central Place and Hierarchy
One of the most scientific models of construction of settlements that affects socio-economic development programs in different countries and regions is the central place theory of Walter Christaller (1969-1873) 1   simplest form by using mathematical tools, and there is usually a direct relationship between the number and diversity of activities and the city's population. Therefore, it can be said that cities that are located on higher levels have more population. In this case, the city on the first level is the smallest city in the urban hierarchy, and the city on the top level has the largest city in that urban system.
From the other features of urban hierarchy based on the theory of central places, the distance between the cities in each level with the class in which those cities are located has an opposite relation. So that the distance between the cities on lower level is less than the distance between the two cities that are on the upper level [8][9][10].
The central places in one geographical area in each region are one of the larger population centers than the other centers, and the amount of goods and services provided in this larger center is more than the centers around it 6 and the direct relationship between work, the size of the population centers with Volume of goods and services provided. In other words, the centers that do production activities in order to produce, supply and service are there. Now these centers can either be subordinate and main centers within a city or the city itself is considered as a production center in an urban distribution system. The central place model only has the ability to explain the trading relations of the settlement. It is important when these centers may be in a region, but not necessarily all or some of them are centralized in a settlement, but also have different settlements of different centers and different rankings in the hierarchy 7 . In this model, the first class settlements and the settlements located at the nearest distance to the center have the most common cultural interactions with the center, and as the distance from the center increases, settlements become smaller and less important where the proportion of local production increase to the productions affected by the center 8 . Walter Christaller, bases his theory on a set of assumptions, summarized in the following: the existence of a flat plain, in which, equally, transportation is possible in all directions. There is only one vehicle in the plain.
The population has spread evenly throughout the plain. In central places in the plain, for spheres of influence, goods and services are prepared and administrative functions are created. Consumers go to the nearest central place that supplies the goods and services they need. Here, consumers traversed minimum distance to receive goods and services. The suppliers of goods and services economic people and they always try to achieve maximum profits in the plain, and as people considering economic advantage come to the nearest center, the suppliers of goods and services get away from each other to attract more consumers 9 . In this plain, in some central places, more functions are offered. These central places are at the higher levels of the central hierarchy system, while places that only have multiple functions, work at lower levels of the hierarchy system.
At higher levels of the Central places and Hierarchy system, all 1 Inomata and Aoyama 1996. 2 Nakoinz, 2012. 3 Brown 1995. 4 Nakoinz 2012. 5 Inomata and Aoyama 1996. 6 Hole 1980, p. 29. 7 Garajian 2003. 8 Minc 2006. 9 Brown 1995. functions, including functions of lower levels of the system, are also offered. All consumers are in the same position in terms of income and demand for goods and services. In this model, different centers of the settlement system are only known and explained by the type and number of goods, the market for the sale of goods, services, employment and population [11][12][13][14].
This theory is presented in the form of spatial view and space, local and temporal volumes of all activities that human beings do to dominate nature and survive. In summary, for the use of the central place model in archeology and for the ancient settlements, the following discursive-hypothetical steps are considered and taken into account in accordance with the available information from archaeological surveys and population estimates: The hierarchy is based on the functional size of the settlements.
II. There is a direct relationship between the functional size and the number of types of goods and services produced in a settlement.
III. The functional size has a close and positive relationship with the population.
IV. The area of a settlement is according to its population. As a result, based on the area of settlements, the population of the sites is estimated and the functional size of the settlement determined based on the population size and then the hierarchy of settlements in the central place model determined by comparing the functional sizes 10 . Another thing that,in addition to the above, can turn a site to a central place, the geographic factors of the location of the site, such as close distance to mineral resources, rich soils, permanent water resources, can also be a factor in turning a site into a central place 11 . In archeology, there is a close relationship between the size of the ancient places and the degree of their social and economic complexity (not necessarily), without understanding and studying it, archaeologists cannot understand the cultural structure of the region. In this hypothesis, the location of larger settlement, it provides more administrative and social services and therefore it has more complex administrative and economic structure than the smaller onesand usually the role factor and function of the sites and the extent of the ancient sites are determining factor of the settlement ranking position 13 , because in sites with more area, more goods and services are provided than areas with less space 14 [15][16][17].

Cluster Analysis of The Central Plase and Hierarchy of The Middle Chalcolithic Settlement
In the Laran County, 16 sites of the middle Chalcolithic were identified, except for the three sites of Kouganak, Khan Yordi and Derazdarreh 1, which were also inhabited from the early Chalcolithic period, the remaining sites including the Ahmadabad It seems that the hierarchical pattern of this cluster is linear [18][19][20][21].

Settlement pattern B
This settlement pattern consists of a site known as the  Laran district. Based on these analyzes, three clusters have been obtained, each one is separately discussed below [31][32][33]. 18 Carr 2003, p. 125. 19 Alizadeh 2010, p. 364. 20 Zagarell1989. 21 Hole 1987. 22 Barth 1964. 23 Saydaei and Dehqani 2011, p. 15. of 3000 meters one site and more than 3000 meters two sites are located which have almost a regional focus. What more indicates the regional focus of these sites is locating in a variety of slopes and pasture vegetation that is common to all sites of this cluster.
The small extent of the sites compared to other groups, high slope and the high altitude of the sea level compared with the other two groups, more distance from water resources than the other two groups and pasture vegetation seems that these sites are temporary settlements where the subsistence of their inhabitants isnomadic livestock. Zagarell calls these types of sites,"slope sites".These sites are less than 0/4 hectares and are located in hills, slopes, and nonagricultural regions of poor soil. Zagarellattributes these types of settlements to moving nomads [34][35][36][37].

Settlement pattern B
The settlement pattern B consists of two sites of the Kouganak mound (code 232) and Kholak(code 432)( Figure 5). Altitude from the sea level of this settlement pattern is between 2140 and 2232 meters and the distance from the communication paths is between 18 and 80 meters. These sites are located in a distance of 143 to 695 meters from permanent water resources and a slope of 5 to 8 percent. The area of this group of sites is between 8400 and 9100 meters, and the height of the cultural layers is to 14 meters. In terms of slope direction including slopes 2 and 4 means northeast and southeast, and in terms of vegetation, they are also located on lands with ability of irrigation agriculture. In terms of locating and distance of the sites in this pattern, it can be noted that these two sites are 41 km apart, so that Kouganak is located in the north and Kholak in the southernmost part of the region. As stated, these sites are located in the final parts of the region, in the vicinity of them are the main roads of the Kouhsefid and Täräz, and one of these sites, the beveled-rim pottery of the Kouganak mound has been obtained. The beveled-rim pottery and Uruk pottery from this site show that these types of sites have not been merely biological 24 Zagarell 1982, p. 64. 25 Algaze 1993, p. 63. 26 Bahraminia et al. 2014. 27 Blench 2001, p. 14. 28 Henrickson 1994. 29 Zagarell1989. 30 Henrickson 1985. 31 Abdi 2003. 32 Mortensen 1974. 33 Wright 1987, Fig. 33a. 34 Alden et al 1982. 35 Abdi 1999aAbdi , 1999bAbdi , 2002Abdi et al 2002Abdi et al , 2003Zagarell 1975aZagarell , 1975bZagarell , 1982Zagarell , 1989 function and probably related to controlling the communication paths 24 . Usually, the distribution of Uruk materials is seen in sites that are capable of controlling high routes and in Zagros these routes are mostly East-West, and most of these routes are located along the river or in pathways and passages between mountains 25 .
The other thing is that these sites are located on the sedimentary terraces of Zayandeh-Roud and Gorgak. Usually, the beds and edges of the rivers are considered to be the best location for agriculture because of the alluvial soils. In other words, the locating of fields along the permanent rivers with rich agricultural soils, lower altitude, proximity and easy access to communication routes, slopes less than ten degrees and rich surrounding pastures have the potential to establish settlements with agricultural economics 26  resources. The area of this site is 5600 meters and its slope is 9 degrees with direction of the eastern slope, and in terms of vegetation is located in pasture and poordry farming lands.The site is also similar to the pattern A considering the height from sea level, the breadth, the slope degree, the distance from the water resources and the communication paths, and the only factor that makes it stand in a separate pattern is its greater extent than the other sites in the settlement pattern A. Generally, these seasonal sites located in outlying regions are called "solitary site" which are made up of a few families 29 .
Regarding the central places and hierarchy of the Laran district, it should be noted that the theory of the central place of the Christaller does not apply in this field, because according to this theory, in each geographic area of a region, one of the population centers is larger than the other centers, and the number of goods and services is supplied in the center, is more than the other peripheral centers.
Although this pattern can be surveyed in regions without natural obstacles and enclosing factors such as mountains, valleys, large rivers and deserts that prevent the dispersion of places, although the vast expanse of a site can not only be an absolute indicator for determining a place is considered as a central place, but it can be considered as an important factor in determining a central place.
In late Chalcolithic in the central Zagros 30 , Islamabad 31 , Huleilan 32 , the highlands of the edge of Susa plain such as Izeh 33 , and Susa, also have a three-rank pattern similar to Laran, and include large, medium and small sites 34 , in this regions, Large sites such as Susa, covering about 11 hectares in this period, as a central site, average sites of 2 to 4 hectares are considered as small villages and small sites less than one hectare are considered seasonal. While all sites of the Laran district have an area of less than one hectare. The largest of them is the Kouganak and Kholak with an area of less than one hectare and, given the above, cannot be called a major central place such as the sites of Khuzestan plain. As we know, in the mountainous region, especially in the studied area, the relationships between the sites are more of an intra-regional type because of the distances between them, although the extra-regional type is also seen.In this way, most of the sites are centralized and the system of these sites is basically anethnical-tribal type. For this reason, habitants of such sites generally have inter-tribal relationships. The evidence of this type of relationship is best appeared in the standardization of their ceramics, which the author has observed among standard are usually similar to similar pottery findings, which have also regional correlations, and are kinship settlement, and sites such as the Kouganak, from which the beveled-rim pottery have been obtained, and in terms of Location are located alongside the main communication paths, calledsites with local centrality 36 .
With regard to the above, it can be concluded that the late  44 . It is also found on the Kouganak mound, and it seems that during this period, the nomads were controlling important communication routes between the central plateau and Khuzestan that crossed the area 45 ; therefore, given the above, it can be said that Kouganak is a seasonal settlement that is located alongside the main route, and this route is probably controlled by nomads.

Conclusion
Christaller beliefs about hierarchical system of habitat relies more on commercial and transportation principles. These habitats are categorized at the national level into higher-ranking, lowerranking, the lowest-ranking, and certain central places. Then, the centrality of a place reflects its relative importance in ranking of hierarchy. The basis of Christaller theory is based on the order of number, size, distance and spatial arrangement of the central places according to their function and hierarchy in their habitat. Christaller believes that central places can be the result of the separation of socio-political or cultural issues. Major administrative centers and their subsidiaries are designed for administrative facilities that do not necessarily follow economic logic. In the same way, border towns that are largely built for defense purposes are settled in such a way that they do not have much sphere of influence. Regardless of these issues, the Christaller implements his viewpoint in a flat plain, while urban and rural settlements in their limited area have many physical and natural barriers to development, affecting environmental and topographical factors, while taking into account a flat region is one of the necessities of this theory. According to the above descriptions, it is not possible to justify the hierarchy patterns between the ancient sites of Laran County according to the pattern of the central place and hierarchy of Christaller, but it 36 Zagarell 1989. 37 Johnson 1983. 38 Digard 1981, p. 63. 39 Barth 1964. 40 Seydayi and Dehqan 2011, p. 15. 41 Alizadeh 1997. 42 Alizadeh 1992. 43 Alizadeh 2010, P. 354. 44 Zagarell 1989. 45 can be justified on the basis of the social and political structure by the allegory method in the region itself. The social and political structure of the Bakhtiari tribe in terms of hierarchy follows a traditional and accurate system and is based on the connections and correlations of the blood, relative or affinity, and economic that they have and living in a geographical limited area.The study of hierarchy and the central place of the sites ofthemiddle and late Chalcolithic period of the Laran district indicate that in the middle Chalcolithic period, like in other adjacent regions of the area, there is a two-rank pattern, and in the late Chalcolithic period, a three-rank pattern of that are similar to the present-day settlements in the region.Today, in theLaran district, the towns of Sudejan are located in the north and Sureshjan in the south of the region, which are considered to be the largest residential areas and are at the apex of the hierarchy pyramid. The remarkable thing is that the two Kouganak and Kholak sites, which are the largest sites of the Laran district, are located far away from these two cities. The second rank among the cities and villages of today Laran district is the newly established Haruni (the old big village), which still located next to the second rank site is called KopoliKolah with an area of half a hectare.Other villages in the Laran district are in the lowest rank or rank 3, which are similar to the same pattern among the Laran district sites with an area of less than 3000 square meters. In general, it seems that the Laran district, in accordance with its environmental conditions, in the prehistoric periods, synchronizedwith other Zagros valleyshas passed its cultural developments.