An arid interior desert–plateau region west of the Rockies, including the Great Basin, Mojave, Sonoran margins, Colorado Plateau, and Basin-and-Range system. Water scarcity forces settlement into river corridors and highland oases. Geography creates resilient, localized societies — from ancestral Puebloan worlds to modern resource-based and urban-basin centers. The plateau–basin structure isolates cultures but also creates distinct high-desert civilizations.
