The Palaeolithic occupation of southern Alentejo: the Sado River Drainage Survey

The Sado River Drainage Survey project (2004-2008) was designed to fill a significant gap in our knowledge of the prehistory of Portugal. Southern Alentejo constitutes nearly one third of the total land mass of continental Portugal, but has received comparatively little attention from Palaeolithic archaeologists. Practically nothing was known about the prehistory of the Sado River basin, which includes the southern Alentejo plain, before now. The results of the Sado River Drainage Survey (SRDS) indicate that the Sado River basin was likely occupied at low population densities during the Middle Palaeolithic. There is some evidence for a Lower Palaeolithic presence but little or no evidence of an Upper Palaeolithic occupation. The emerging pattern suggests either an occupational hiatus or a major shift in settlement pattern towards the end of the Middle Palaeolithic. Possible explanations for this pattern, including aridification driven by climate change, are explored here.