As an archaeologically less-known region, Southwest Arabia offers new insights that can contribute to interregional understanding of agriculture's beginnings. The relative importance of environmental and social factors is an issue that has proven particularly contentious for both general and regionally focused explanations of transitions to agriculture. Geomatics analyses of landforms and runoff and ethnoarchaeological consideration of cairn tombs and water rights along the Wadi Sana drainage of Hadramawt Governate, Yemen, highlight the joint importance of two proximate dimensions of environmental conditions and social relations-hydrology and ideologies of territoriality. In contrast with a focus on one or the other, perspectives that draw on the strengths of both scientific quantification and humanistic interpretation provide for more accurate understanding of the circumstances that shaped the lives and livelihoods of early farmers.(revue)