doi: 10.2143/TE.49.0.3248524 Trans 49, 2017 DRY CLIMATE DURING THE EARLY PERSIAN PERIOD AND ITS IMPACT ON THE ESTABLISHMENT OF IDUMEA (Pls. VII-IX) D. LANGGUT* AND O. LIPSCHITS** Summary: In the 8th-7th centuries BCE the southern border of Judah included the southern Lowland (Shephelah), the southern hill country and the Beer-sheba– Arad Valley. In this southern fringe of Judah, Judeans lived side by side with tribes that were of Edomite and Arab origin. In the 4th-3rd centuries BCE the Province of Idumea included all the areas of the Beer-sheba–Arad Valley, the southern Shephelah and the southern Judean Hills; the majority population in the region was Idumean and Arab. The borders of Yehud had shrunk to a line north of Beth-Zur in the hill country and Azekah and the Ellah Valley in the Shephelah, and most of the Judahite population was concentrated around Jerusalem. Expla- nations for these historical, geopolitical, cultural and demographic changes have been well-discussed by scholars; in this paper, we provide a set of paleo-envi- ronmental data that sheds new light on this process. Palynological and sedimen- tological information show that during the late 6th through the mid-5th centuries BCE (~ 520-450 BCE) dryer climate conditions were prevalent in the region. During the early Hellenistic period, wet climate conditions and intense olive horticulture characterized the region. Since in the steppe-marginal areas of the southern Levant, even minor climatic variation can result in major environmental change, the main argument of this paper is that the dry conditions in the early Persian period caused a process of abandonment of most of the villages in the southern parts of the former Kingdom of Judah, triggering nomadization of some elements of the local population and immigration to the core areas of the prov- ince of Yehud of others. After the destruction of the Kingdom of Judah and the collapse of the southern settlement and military system, this process provoked a demographic vacuum in the southern Lowland (Shephelah), the southern hill country and the Beer-sheba–Arad Valley that encouraged the immigration of nomadic elements into it. The gradual increase in moisture in the late 5th and 4th centuries BCE probably reinforced a cultural progressing, by stabilizing the * D. Langgut, Laboratory of Archaeobotany and Ancient Environments, Institute of Archaeology, Tel Aviv University, Tel Aviv 69978, Israel. langgut@post.tau.ac.il ** O. Lipschits, Professor of Jewish History, Director of Sonia and Marco Nadler Institute of Archaeology, Tel Aviv University, Tel Aviv 69978, Israel. lipschit@post.tau.ac.il