region of the Sahara lying in southern Algeria and northern Mali. Covering part of a plateau eastward toward the Ahaggar (Hoggar) uplands, it slopes to lower ground in the west, and farther southward lie swamps. The region lacks water, landmarks, and vegetation. It was formerly shunned by caravans but is now spanned by a trans-Saharan motor route going north-south from Béchar (Alg.) to Gao (Mali) and beyond. Poste Maurice Cortier is a fueling station on a north-south caravan route. Tanezrouft is inhabited only by a few Tuaregs. There is a vast water-bearing stratum a few thousand feet below the surface.