GoKawiilStudy: Lack of toolmaking stone, not water, kept Stone Age humans out of Rub' al Khali interior
Researchers surveying 55 ancient lake sites across the central Rub' al Khali desert found no stone tools from the Middle Palaeolithic/Middle Stone Age, despite abundant freshwater lakes and nearby human occupation at the desert margins. They attribute this absence to the region's carbonate and evaporite geology, which lacks the fine-grained silicate rock needed to make stone tools, rather than to any lack of water or population capability.