Patagonian Desert albeit to the west, where precipitation is higher, bushes are replaced by grasses. Topographically the deserts consist of alternating tablelands and massifs dissected by river valleys and canyons. The more western parts of the steppe host lakes of glacial origin and grades into barren mountains or cold temperate forests along valleys. Inhabited by hunter-gatherers since Pre-Hispanic times, the desert faced migration in the 19th century of Mapuches, Chileans, Argentines, Welsh, and other European peoples, transforming it from a conflictive borderland zone to an integral part of Argentina, with cattle, sheep and horse husbandry being the primary land uses. The Patagonian
Monte Desert other two nearby deserts. The geography of the land is very similar to that of the interior Patagonian Desert, with volcanic sediments, piedmont plains, large mountain blocks and many usually dry salt lakes. The major river is the Río Colorado and its tributary the Río Desaguadero, which meet in the south of the region and provide its principal source of irrigation water for wine crops. Due to the region lying on the eastern, or leeward, side of the Andes and west of the Sierra de Córdoba, it experiences very little rain. These rain shadow effects are the primary reason for