in North America, ancient cultures centred on the Great Basin in the area of Nevada, Utah, and Arizona; they lasted from about 7000 or 8000 BC to about 2000 BC. Subsistence was based on gathering wild seeds and plants and on hunting small game; social groups were probably small and nomadic. The people used baskets, nets, crude milling stones, simple bone tools, and stemmed or notched chipped-stone projectile points. See also Cochise culture.