An insight into the geomorphological characteristics of Holeylan as well as its suitable environment in the Central Zagros convince us that it has a capacity, more than ever shown, in presenting Paleolithic sites. Thus, the necessity of doing an intensive archaeological survey in this valley with the aim to explore the Paleolithic sites became apparent and was achieved only in the autumn of 2015. The research questions are mainly based on the number of sites, their type and size, geographical variables influencing the site selection patterns among the Paleolithic societies, tool making techniques and identifying raw material sources in Holeylan. During the survey, 103 sites, including 24 caves and rock shelters as well as 79 open air sites were identified with utilities such as residential compounds, seasonal camps and hunting ambushes. Among them, only one of the rock shelters was situated in the eastern most part of the valley. The open air sites formed on the natural hill tops with terraces overlooking Seymareh and Jezman Rivers and their tributaries. Climate and tectonic features seem to be the two main reasons that made Holeylan as one of the most important valleys of central Zagros during the Paleolithic era. Moreover, water resources and its elevation above the sea level were the most important components which led settlements access to raw materials. Chert pebbles and cobbles accumulated in the bed by rivers were resources of tool making in Holeylan Valley during the Paleolithic period.
