A hunting-and-gathering way of life adapted to the post-Pleistocene conditions of the arid and semi-arid zones of the American West from Oregon to California, and with extensions into similar areas of Mexico. Agriculture was unknown or unimportant, and the small nomadic bands lived by collecting wild plants and hunting game. The concept was devised by J. Jennings at Danger Cave. Typical artifacts include grinding stones, basketry, small projectile points, and spear throwers. There is an absence of ceramics. Their mode of subsistence was established c 9000 BC and lasted until agriculture had developed sufficiently to permit settled life. In Mexico, farming villages were widespread by 2000 BC. In the southwestern US, this did not occur until the last few centuries BC.