Abstract
The concentration of activities and sites Iron Age excavations carried out in Iran in the quarter-northwest Iran. It covers the west, northwest, north of the center, and the west bank of the Caspian Sea. The important point is that the chronological basis of the Iron Age in Iran is also based on the excavation of several sites in a small part of the northwest and its extension to the whole of Iran. Thus we see the Iron Age archaeological activities at the eastern part of Iran and especially North East is very unknown. Iran has long been the entry point for people without a nomadic component steppes of northeastern North Asia region is the Iranian plateau. According to written sources the oldest nations that have entered the Iranian plateau, known as the Indo-Iranian or Aryan tribes from the steppes of northern Asia to the south and in the land of the Pamir Mountains to Anatolia widely dispersed. Many scholars consider the gradual movement of these tribes to be from the second millennium. A period that is almost synonymous with the Iron Age in the region. But our knowledge of the Iron Age northeastern Iran today virtually all North Khorasan Province and the northern part of Khorasan Razavi province involved is negligible. This paper is based on the latest research picture of the Iron Age northeastern part of the country, with emphasis on the upper basin Atrak be provided. According to the study and identification carried out in this basin, the Iron Age of the upper Atrak basin is part of the Yaz 1 culture.
Keywords: Northeastern Iran, Iron age, Upper Atrak basin, Yaz 1 Culture, Archaic Dehistan, Settlement Patterns.

Introduction
It has been less than a decade that steps have been taken to understand the Iron Age in Northeastern Iran through surface explorations and excavations. Based on this, it seems that some parts of northeastern Iran are in the cultural area of Archaic Dehistan and another part is in the cultural area of Yaz I (Basafa 2017, Dana & Hejebri Nobari 2019, 2021, Vahdati 2016, 2018). The upper Atrak basin is an almost rectangular valley with a length of 90 km and an average width of 20 km. This region is one of the most important regions of northeastern Iran in terms of population movement because it connects the north of Kopet-Dagh to the interior regions of Iran and the center of the Iranian Plateau (Fig.2). Northeastern Iran has long been the place of entry of nomads from the northern steppes to the inner regions of the Iranian plateau. Due to the geological feature, Kopet-Dagh act as a barrier between the Karakum desert in the north and the fertile areas in the south, which cannot be crossed except through a few natural passages. 
More than 500 sites were identified in the archaeological surveys of the upper Atrak basin, among which 23 sites were dated to the Iron Age (Fig.3).

Iron Age Sites in the Upper Atrak Basin
The 23 Early Iron Age sites identified in the upper Atrak basin are listed in Table 1. In the surface survey of these sites, the only available data was pottery. In all Iron Age sites of this basin, the dominant pottery is Yaz 1 hand-made pottery. These pottery are poorly made, rough and in the range of buff and bright red, and the motifs are usually drawn geometrically with ocher and jujube red colors, and most of them are mixed with grog. 9 of the identified sites can generally be attributed to the Iron Age, and traces of Yaz I painted pottery were not found in the surface surveys. The pottery of these 9 sites are similar in form to the pottery of the Archaic Dehistan culture, but unlike them, they are in the buff and red spectrum.

Location based on ٍlevation Factor
The Iron Age sites of the region are located at an altitude between 1007 and 1718 meters above sea level. The size of the smallest site is 0.01 and the largest is 10 hectares. Examining the Pearson correlation coefficient regarding the area of the enclosures with the height factor shows -/299 (Table 2), which indicates a negative but moderate correlation. This means that as the height above sea level increases, it is expected that the size of the enclosures will decrease due to the limitations of natural factors.

Water Resource Factor
The distance of the Iron Age sites in the region from permanent water sources, including rivers and other running water sources, ranges from 0 to 6395 meters, and their average distance is 1441 meters. Pearson correlation coefficient/313. (Table 2) states that this figure shows the relationship between the direct and average level of significance between the size of the sites of the region with the factor of distance from permanent water sources. 

Land Use Factor
Pearson’s correlation coefficient between the size of the sites of the region with the soil type factor of the location of the sites shows -.054 (Table 2). This figure is weak and small. It is expected that there are large sites in the sedimentary plains and smaller sites on the edge of the plains and mountain slopes, and this is not the case in this area.

Slope Factor
Pearson’s correlation coefficient between the sizes of the sites of the region with the slope factor of the location of the areas is 0.72. (Table 2). The figure shows a very weak relationship between the size of the sites and the degree of slope of their location. 

Slope Direction Factor
Pearson’s correlation coefficient between the size of the sites of the area with the slope direction factor of the location of the areas shows -240 (Table 2). This phenomenon shows that some of these sites have not been used for a long time or that the different slope directions were not so important for the residents of this site in different seasons.

Communication Routes Factor
The sites of the region are located at a distance between 0 and 15355 meters from the main communication routes today. The Pearson correlation coefficient shows -114 (Table 2), this figure shows a very weak and small and inverse relationship. In other words, as we move away from the main communication routes, we should expect the size of the enclosures to decrease and become smaller.

Distribution of Iron Age sites in the Upper Atrak Basin
In this research, in order to obtain the distribution pattern of settlements in the region and to better analyze and understand the distribution of archaeological sites in the region and to find a pattern that fits environmental variables, the statistical method of cluster analysis has been used. Based on statistical analysis and their clustering, three patterns were obtained (Table 3, Chart 1).
Settlement distribution pattern 1: Settlement distribution pattern 1 includes 6 enclosures (Chart 1, Table 3). Due to the location of these types of sites in the landscape of the region and according to the distribution of these settlements on the level of the plain and the highlands, their small size, which is less than half a hectare, the economic method of these habitats can be assumed as temporary and seasonal settlements.
Settlement distribution pattern 2: There are 14 enclosures in this pattern (Chart 1). Due to the location of these types of sites in the landscape of the region and according to the distribution of these settlements on the level of the plains and the highlands, their small size, which is less than two hectares, the economic method of these habitats can be assumed as agricultural and livestock settlements.
Settlement distribution pattern 3: There is only one site in this group, and the reason for their placement in a cluster or separate pattern is its very large area compared to other sites. The size of this site is 2.2 hectares. The characteristics of this site, especially being located at a high altitude and a long distance from water sources and communication routes, and other characteristics show that it is similar to model 1, and only because of the difference in the size of this site, it is placed in a separate group.

Conclusion
The largest sites in the upper Atrak basin (except the IUA03 site) are located almost in a vertical line and very close to each other, Tappe Yam with 10 hectares, Tappe Ja’far Abad with 2.8 hectares and Sofalgaran-e Zadak site with 3 hectares, for a total of about 16 hectares from the total 33 hectares, half of the size of the Iron Age sites cover this basin. Today, these sites are located around the city of Faruj and almost in the middle of the plain. This area can be considered as the crossroads center of important roads in the region.
The important point in the reconstruction of the roads is the mountainous conditions of the region, which does not allow passage anywhere. With these conditions, there is only one possible way in the south, and that is today’s Binalud-Shah Jahan road, which goes from Quchan to Sabzevar. Near this road, there is Tappe Golshan Abad, which is actually located in the entrance area of this mountain pass. 
However, it is a little difficult to determine the northern route to pass Kopet Dagh and go to its north due to the number of valleys and the connection of some valleys with each other. By carefully examining the existing routes in the area and their connection with the Iron Age sites, a route is suggested that includes the sites of Tappe Yam, Dalan Tappe Kukach, Dalan Tappe Bozorg and Unnamed Tappe of Milanlu.
The western road along Atrak River connects the upper basin to the middle Atrak basin.
The eastern road also continues to the Kashaf River basin and the Mashhad plain without any natural obstacles.
Today almost all researchers agree that the people had Yaz I culture, nomads. Since Yaz I remains in a wide area of Greater Khorasan and the southern parts of Transoxiana, the route of population migration will inevitably pass-through Greater Khorasan through the north-south routes that connect the steppe regions of North Asia to its inner regions in the Iranian plateau. In this view, the upper Atrak basin is located in the area of Yaz I pottery culture, and due to its strategic location, it plays a very important role in the arrival of people with Yaz I culture to the inner parts of the Iranian plateau.