Archeologists believe that the first people came to America at least 15,000 years ago in several groups or tribes. The first Americans came from Asia following herds of grazing animals across a land bridge formed during the Ice Age. When the Earth began to warm, this land or ice bridge melted and became the Bering Straight. The people journeyed on foot slowly southward into North American through a harsh landscape. They were expert hunters and speered huge animals such as the Woolly Mammoth and the Long-Horned Bison.