Stone and water governed early human settlement of the desert.

Stone availability for tool manufacture independently governed early human settlement across the Rub' al Khali, with no lithic artefacts found despite abundant freshwater along a 1,500-km transect.

• Why it matters: Dispersal models often assume freshwater alone controls where populations can settle, but brief, geographically constrained Pleistocene dispersals into “Green Arabia” are not explained by water availability.
• What they did: The study conducted an approximately 1,500-km geoarchaeological survey through Arabia’s Rub' al Khali, recording palaeolake deposits at 55 of 125 localities and testing spatial models linking settlement to water plus knappable lithic raw materials.
• The result: Settlement tracked the co-occurrence of water and lithic raw materials rather than water alone, improving discrimination of known sites from an area under the curve of 0.695 to 0.768.