The Cenozoic harrats (lavafields) of western Arabia constitute one of the major volcanic areas of the world. Recent precise chronometric dating of volcanic rocks in Harrat Rahat makes it possible to outline a detailed chronology of volcanic activity. Likewise, recent advances in archaeology have demonstrated that early humans repeatedly occupied the Arabian Peninsula in the Pleistocene. Most archaeological sites in Arabia correlate with phases of increased rainfall, such as interglacials. However, we should be cautious about reducing the prehistory of Arabia to simply the story of rainfall fluctuation. This paper explores the impacts of volcanism on human populations in Arabia, as a case study of causality and scale in human-environment int...