As the final ice age came to an end, the weather in North America became warmer.
Over many centuries, the descendants of the people who crossed the Bering land bridge traveled farther and farther south, then east. They were always searching for new animals to hunt, in part because the weather changes were causing the mammoths and other large prehistoric animals to die out.
By about 11,000 B.C., there were Native Americans living in all areas of the continent, all surviving by different methods of hunting, fishing, and gathering wild plants.
Slowly, as they adapted to their new environments, different groups of people began to develop different cultures.