of an extended family, moving from place to place as resources were depleted and additional supplies needed. Paleoindian groups were efficient hunters and created and carried a variety of tools, some highly specialized, for hunting, butchering and hide processing. These paleolithic people utilized the environment that they lived in near water sources, including rivers, swamps and marshes, which had an abundance of fish, and drew birds and game animals. Big game, including bison, mammoths and ground sloths, also were attracted to these water sources. At the latest by 9500 BCE, bands of hunters wandered as far south as Arizona, where they found a desert grassland and hunted mule deer, antelope and other small mammals. As populations of larger game began to diminish, possibly as a result of intense hunting and rapid environmental changes, Late Paleoindian groups would come to rely more on other facets of their subsistence pattern, including increased hunting of bison, mule deer and antelope. Nets and the atlatl to hunt water fowl, ducks, small animals and antelope. Hunting was especially important in winter and spring months when plant foods were scarce. Archaic period The Archaic time frame is defined culturally as a transition from a hunting/gathering lifestyle to one involving agriculture and permanent, if only seasonally occupied, settlements. In the Southwest, the Archaic is generally dated from 8000 years ago to approximately 1800 to 2000 years ago. During this time the people of the southwest developed a variety of subsistence strategies, all using their own specific techniques. The nutritive value of weed and grass seeds was discovered and flat rocks were used to grind flour to produce gruels and breads. This use of grinding slabs in about 7500 BCE marks the beginning of the Archaic tradition. Small bands of people traveled throughout the area, gathering plants such as cactus fruits, mesquite beans, acorns, and pine nuts and annually establishing camps at collection points. Late in the Archaic Period, corn, probably introduced into the region from central Mexico, was planted near camps with permanent water access. Distinct types of corn have been identified in the more well-watered highlands and the desert areas, which may imply local mutation or successive introduction of differing species. Emerging domesticated crops also included beans and squash. About 3,500 years ago, climate change led to changing patterns in water sources, leading to a dramatically decreased population. However, family-based groups took shelter in south facing