TRACKING RAINFALL AND ANCIENT EMPIRES SINCE THE LATE BRONZE AGE IN THE JIROFT VALLEY, SOUTHEASTERN IRAN

The Achaemenids and Sasanian 'Persian' Empires were significant political, economic, and social forces in Late Bronze Age and Late Antiquity Eurasia, respectively, and have left distinct marks on the heritage of the Mediterranean and Middle Eastern world. While much attention is often focused on military and political factors when discussing the prosperity and decline of these imperial powers, their realms, which crossed a variety of environmental settings, were highly dependent on the predictability of rainfall that drove agriculture and effective provisioning. Here, we present a multi-proxy sedimentological, geochemical, and palynological record from a 2.5-m long peat deposit from the Jiroft Valley in southeastern Iran covering 4011 to 854 cal yr BP. At ca. 3950 cal yr BP a wet period prevailed based on the proxies low Ti/Al and Si/Al and high K/Al, high δ¹³C_OM, low C/N, high P_aq, and low CPI values. Between 3900 and 3293 cal yr BP, mild conditions developed with the significant appearance of Cerealia-type pollen. Dry and windy conditions followed from ca. 3293 to 2897 cal yr BP with the driest conditions centered around 3200 cal yr BP coinciding with the intensity of the Siberian anticyclones and a regional climatic shift in the Eastern Mediterranean. After that, a prolonged wet period extending from 2897 to 2302 cal yr BP with a high abundance of Sparganium-type pollen and P_aq coincided with intensive agricultural practices and the flourishing of the Median and Achaemenid empires. The shift to high Ti/Al values coeval with the lowest δ¹³C_OM values suggests an increase in aeolian activity and dry conditions between 2100 and 1650 cal yr BP. The Jiroft valley again experienced wet conditions between 1540 and 1315 cal yr BP, which overlapped with the economic prosperity of the middle to late Sasanian Empire. The paleoenvironmental reconstruction indicates that wet periods and intensive agriculture coincide with the Persian empires' political zenith and economic affluence. Hence, contextualized and detailed palaeoenvironmental records are desirable to explore the interplay of political and climatic factors in the development and fragmentation of some of the most renowned Empires in Eurasian history.