The Great Basin culture area, an expansive bowl formed by the Rocky Mountains to the east, the Sierra Nevadas to the west, the Columbia Plateau to the north, and the Colorado Plateau to the south, was a barren wasteland of deserts, salt flats and brackish lakes. Its people, most of whom spoke Shoshonean or Uto-Aztecan dialects (the Bannock, Paiute and Ute, for example), foraged for roots, seeds and nuts and hunted snakes, lizards and small mammals. Because they were always on the move, they lived in compact, easy-to-build wikiups made of willow poles or saplings, leaves and brush. Their settlements and social groups were impermanent, and communal leadership (what little there was) was informal.