Abstract
Most of our knowledge on the Palaeolithic of the Iranian Plateau derives from a scientific focus on the area of the Zagros Mountains. In recent years, several Palaeolithic research projects have been conducted in different parts of Iran, including southern piedmonts of the Alborz Mountains and the Iranian Central Plateau. The present paper is an introduction to the archaeological pieces of evidence of a Palaeolithic occupation on the southern slopes of the Alborz Mountains. Sorheh Rockshelter is the first site among a cluster of 8 caves and rock shelters located around 80 km northwest of Tehran. The Palaeolithic artifacts have been recovered from at least three looters’ pits at the center of the rock shelter. Sorheh is significant at least for two aspects: firstly, since the southern slopes of the Alborz Mountains have not yet been identified for the Palaeolithic, the site provides unique data on the Iranian Plateau. Secondly, the site’s location and the physiogeographic and lithic analyses of Sorheh are invaluable for the reconstruction of hominin behavior and settlement patterns in this under-researched area. 
Keywords: Central Iranian Plateau, Alborz Mountains, West-Central Zagros, Middle Palaeolithic, Levallois.

Introduction
Compared to the wealth of Palaeolithic data from the Zagros region, the piedmonts of the Alborz Mountains have received little scientific attention. The focus has been on the northern slopes, although the intermountain valleys of the southern Alborz Mountains could have been biogeographically suitable for hunter-gatherers. Since the first systematic efforts of the Palaeolithic research in the Alborz Mountains by Carlton Coon in 1949 (1951, 1957), a few Palaeolithic sites have been discovered in the northern and southern slopes of the Alborz Mountains. Moving from the southern slopes of the Alborz Mountains towards the center of the Iranian Plateau, the number of Palaeolithic sites increases. Especially in recent years, many critical Palaeolithic localities have been identified on the interior plains of the Central Iranian Plateau (Biglari 2003, Masoumi et al. 2010, Eskandari et al. 2010, Vahdati Nasab and Feyz 2014, Vahdati Nasab et al. 2009, 2013, 2014, 2016, Heydari-Guran and Ghasidian 2011, Heydari-Guran et al. 2015, Kaboli 1999).
From the physio-geographical point of view, it seems that the sites located on the southern slopes of Alborz Mountain are related to the inner parts of the Central Iranian Plateau (Heydari-Guran et al., 2015). However, it has always been questioned whether the southern slopes of Alborz, like the northern slopes, were an area of human presence during the Palaeolithic. If so, was there a connection between the inhabitants of the southern and northern Alborz slopes? What about the connections to the inhabitants of the interior plains of the Iranian Plateau? Such questions led the authors to study the valleys located in the Southern Alborz Mountain foothills around 80 km crow flies to Tehran’s northwest. The survey in this region has led to the discovery of a complex of caves and rock shelters. The lithic artifacts from one site, Sorheh Rockshelter, presents new insights into the study of human settlement and behavior during the Late Pleistocene in the Iranian Plateau. 

Sorheh in the Palaeolithic Context of the Iranian Plateau
The Sorheh complex consists of 6 caves, and rock shelters were firstly identified in 2018 by one of the authors (H.H.). The complex is formed in a deep drainage system within tuff, shale, and sandstone lithology along the Senj River. It is located around 19 km north of the modern city of Karaj, at a longitude of 50,957,183 and latitude of 35,992,211, and approximately 1900 m above sea level. The first site of this complex on the west side of the valley, Sorheh Rockshelter, revealed rich Palaeolithic depositions. Preliminary examining the exposed strata and accumulated soil confirmed that the site is rich in archaeological remains.
Five other shelters of the Sorheh complex are located between 20 and 70 m east of Sorheh Rockshelter. They mostly consist of a rocky surface with poor deposition; some were destroyed by the looters’ pits. The bedrock dip in two rock-shelters is towards the front slope caused no preservation of archaeological deposits. The last shelter of this complex is attached to the Senj River and is endangered by periodically river flooding, thus empty of archaeological deposits. The newly-constructed road between the villages of Baraghan at the west to Vamkouh at the east destroyed partly two rock shelters; however, it provided easier access to Sorheh Rockshelter.
In general, the lithic techno-typological characteristics of Sorheh presents significant Middle Palaeolithic elements. These lithic artifacts bear little resemblance to their counterparts from Zagros, such as Warwasi, Bisetun, and Kunji (Dibble and Holdaway 1993, Dibble 1984, Baumler and Speth, 1993). However, a comparison with Zagros sites is not plausible because of the considerable distance between these sites and the Alborz. The sites located in the interior regions of the Iranian Plateau, perhaps, provide more relevant information. Most of the Central Plateau open-air sites, including Chah-e Jam, Mirak, Zaviyeh, and Holabad, are flake-oriented, and Levallois technology has widely been used (Heydari-Guran and Ghasidian 2011, Heydari-Guran et al. 2015, Vahdati Nasab et al. 2013, Vahdati Nasab and Hashemi 2016). Levallois technology was observed abundantly among Sorheh collection, though heavily retouched tools, reminiscent of the Zagros Mousterian, are nearly absent.  
Sorheh’s collection reveals more similarities to two open-air sites of Moghanak and Otchounak. The lithic artifacts from these sites are mostly based on the production of blades and elongated flakes (Berillon et al. 2007). The Levallois technology was broadly practiced in Moghanak and Otchounak. The points from Moghanak are plain and unretouched, reminiscent of the Sorheh points. Due to the lack of characteristic retouched tools in Moghanak and Otchounak, no typological comparisons were possible.

Conclusion
The evidence from Sorheh, Zagros Mountains, and the Iranian Central Plateau indicate various subsistence strategies in different geographical regions. This issue put forward the idea of cultural variability among the Middle Palaeolithic populations (Heydari-Guran et al., 2015) in contrast to the notion of cultural homogeneity (Mousterian) throughout the Iranian Plateau (Rosenberg 1988, Biglari et al. 2009, Piperno 1972). 
Considering the high elevation of 1900 m asl., Sorheh Rockshelter, after Ghaleh Kurd with 2100 m asl., is one of the highest-elevated Palaeolithic sites on the Iranian Plateau. Ghaleh Kurd has revealed Middle Palaeolithic artifacts assigned to the Mousterian techno-complex (Soleimani and Alibeigi 2012). The study of the deposits from Sorheh will provide valuable information on the climatic changes during MIS 5 to 3 up to Holocene. It seems that the area, despite high altitude, periodically provided ideal settlement conditions. Climatic amelioration intervals made the region suitable for settlement. Therefore, the detailed physiogeographic study of the Sorheh complex may provide a wealth of information on late Pleistocene climate changes.
Due to the techno-typological similarities of Sorheh lithics to the sites in the Central Iranian Plateau (Vahdati Nasab et al. 2013, Heydari-Guran et al., 2015), we hypothesize the cultural exchange between late Pleistocene hunter-gatherers of Alborz and the interior parts of the Central Plateau during climatic deterioration periods. 
The discovery of this complex with a particular geographical location in a valley with difficult access and, most importantly, the rich Palaeolithic depositions is an essential step towards answering questions related to the human dispersal at the edge of the Iranian Plateau during Marine Isotope Stages of 5 to 3 stages.
Systematic excavation and acquisition of more data in Sorheh will allow more accurate and detailed comparisons to other Middle Palaeolithic sites of the Iranian Plateau.

Abstract
This paper will focus on Lithic assemblages from three sites in the eastern part of Kurdistan province. The Chalcolithic period appears with different pottery tradi-tions than the earlier period in the Zagros, these changes appear mainly in the emergence of a variety of long blades and very regular and standard sickle blades. Due to the importance and lack of studies on the Chalcolithic Lithic, the main ques-tion in this article is what was the technology and function of the tools in the Chal-colithic period? The results show the technology of direct percussion with a hard hammer used to in the primary stages of Chalcolithic, and in the late phase, in addi-tion to the earlier method, the pressure technique has also been used to construction of long blades and sickle blade. Also, long blades and sickle blades, in terms of production technique, are continued in the Neolithic period in the Zagros, but in terms of dimensions as well as the ratio of blade length to width in a new class which is a new indicator for the Chalcolithic period. The results show that the con-struction of regular sickle blades begins in the late Chalcolithic phase. The skill of making tools is undoubtedly related to exist people who have special ability for these products, and they have distributed these tools in certain areas; because the least waste of high-quality flint of these blades has not been found in the sites. While most of the debris belong to raw material that are easily accessible in the riv-erbed.
Keywords: East of Kurdistan, Chalcolithic Period, Lithic Artifact.

Introduction
The stone artifacts in this study are the result of excavations in Tepe Gheshlagh (Motarjem & Sharifi, 2015; Sharifi & Motarjem, 2018), Tepe Kalanan (Saedmoucheshi, 1390), and Golali (Saedmoucheshi, 1398) in Kurdistan province (Figure 1). In this region, the chronology of Tepe Gheshlagh, one of the key site in the Chalcolithic period that shows the sequence of this period (Motarjem & Sharifi, 2014). On the other hand, all samples of artifacts obtained in intact layer and with absolute chronology (Table 1). The Chalcolithic period in the Central Zagros has been studied by many scholars (see Young & Levine, 1974; Abdi, 2002 & 2003; Henrickson, 1983 & 1985), and most studies have focused on pottery and other data. Various sites in this area such as Godin (Young, 1969), Sehgabi (Young & Levine, 1974) have been explored before the Islamic Revolution of Iran and there isn’t an independent report on the tech-nical classification of stone tools. Study of Lithic artifacts in the Cen-tral Zagros including superficial study of Tepe Ban-Asyab (Bernbek et al., 2011), superficial study of Hersin (Mortensen & Smith, 1977), Chogha-golan and Towe Khushkeh sites in Islamabad plain (Abdi, 2002). Also, the study of lithic tools tradition in the sixth and fifth millennium BC in the Zagros gets limited to (Kozlowski, 1999; Nishiaki, 2013, 2019) and west of Kurdistan (Hariryan et al., 2021). In this regard, the study of stylistic differences in terms of technology, typology, and access to sources of raw material, as well as trade of some stones such as obsidian is momentous. Therefore, research questions include the following: (1) what is the basis of the tool-making tradition in East Kurdistan? And (2) Due to socio-economic complexities that occurred during the Chalcolithic period, what changes have taken place in the Lithic artifacts? The hy-pothesis of this research is that the Post-Mlefaatian tradition of tool making has been prevalent in this region. In fact, the purpose of introducing and analyzing of Chalcolithic Lithic is paying attention to them as cultural data that an important role in cultural communication and interactions.

Conclusion
The study of stone artifacts during the Chalcolithic period and beyond has never been seriously considered in Iranian archeology, this is due to the prevalence of evolutionary archeology. This approach goes back to the Serialization and connec-tion of cultural transformation circles to each other, without an explanatory and an-alytical approach to the lifestyle and cultural exchanges and human dynamism in the habitat. Discussions that were considered only after the spread of new archeol-ogy. The study of stone artifacts in this study shows that the insignificant quantity of tools in the early and middle phases of Chalcolithic, It shows the focus of the residents of this area on livestock. Because the Habitat around Tepe Gheshlagh and Kalanan are mainly steppe and less fertile. In the late phase, the production of Lith-ic tools increases, especially the examples related to grain harvesting, which indi-cates a kind of more attention to crop production. This leads to decline of livestock or the increase of population in the region and even familiarity with new cultivation methods. In the late Chalcolithic, this region has Cultural Horizon with the late Obeid, early Uruk and the Sabz period of Dehloran and Khuzestan. At this time, agriculture based on irrigation has been proposed on southern region such as Susa and Dehloran. In these periods, all the tools used in agriculture, focused on Lithic tools and implements including plowing tools, sickles, mortars and hand tools. In fact, the construction of practical tools, the use of different raw materials, and the interpretation of regular and long sickle blades represent an advanced and evolving technology. The produce of regular sickle blades from high quality stone, disap-pearance of small scrapers (trapezoidal and triangular) and the limitation of serrated tools are the most important changes in this period compared to the Neolithic peri-od. 
Lithic assemblages during the 6th and 5th millennia BCE in the Zagros is known as Post-Mlefaatian tradition (Kozlowski, 1999). The use of pressure Debitage tech-nique to produce long blades and sickle elements is one of the most significant fea-tures of this tradition. In the Post-Mlefaatian, the length of the blades increases. In East Kurdistan, we are faced with two technologies for making stone tools, (1) The use of direct percussion for primarily stage of removing, and (2) The use of pres-sure technology for construction of sickle blades. We have a limited number of long blades in Gheshlagh and Gelali sites, but the construction of these blades, like other regions of the Zagros, shows the use of the Post-Mlefaatian tradition in this region.
It is probable that after 3 to 4 thousand years of domestication of devolving of wheat stem compared to other species such as Emmer and Einkorn of the Neolithic period, In order to harvest, thicker and stronger blades need to create. The produc-tion of thicker blades in this period has been a technical adaptive response to this need. Hence, the discussion over the assumption about the prevalence of irrigation in the Chalcolithic period, even to a limited extent, has led to change in Lithic tools production related to agriculture, especially sickle blades. On the other hand, issues such as the formation of full-time or part-time expert groups, access to high-quality flint mines for proper production, distribution and exchange are raised. As men-tioned in the discussion, there is no evidence of regular sickle blades construction on the site, in the eastern Kurdistan. On the other hand, presence of obsidian in Gheshlagh and Kalanan sites show continuation of the old distribution network of the nearest neighbor to the far regions in eastern Kurdistan. The presence of obsidi-an and lack of evidence for making sickle blades from dark flint, indicate the pos-sibility of making blades produced from this species in specialized workshops out-side the site and their import to these areas.