Peru borders it on the north and the Chilean Matorral ecoregion borders it on the south. To the east lies the less arid Central Andean dry puna ecoregion. The drier portion of this ecoregion is located south of the Loa River between the parallel Sierra Vicuña Mackenna and Cordillera Domeyko. To the north of the Loa lies the Pampa del Tamarugal.