Though we evolved in Africa some 125,000 years ago, humans would not reach the Americas for more than 100,000 years. Man spread into Australia by 60,000 years ago and occupied the Mediterranean region about 50,000 years ago but would not set foot in North America until the peak of the Wisconsin glaciation, some 20,000 years ago.
The great majority of human migrants reached the Americas via the Bering Land bridge, which remained open through most of the late Pleistocene; however, DNA evidence suggests that some of these original inhabitants arrived from Europe after hunting their way along the southern edge of the North Atlantic ice shelf. Those crossing from Asia bypassed the North American glaciers via two routes; some (perhaps most) spread southward along the Pacific coast while others followed herds of mammoths and bison through an ice-free corridor east of the Rocky Mountains. Most archaeological evidence indicates that man was south of the glaciated areas by 15,000 years ago and had spread throughout North and South American by the end of the Pleistocene (10,000 years ago); by 7000 years ago, humans had crossed the Florida Straits and were living in Cuba.
As elsewhere, early Americans were nomadic and permanent settlements did not appear until the Holocene (10,000 years ago). Among the more famous cultures and civilizations to rise in the Americas were the Mayans of Central America (2000 BC to 1550 AD), the Hopewell mound builders of the Ohio River Valley (200 BC to 300 AD), the Fremont People of the Great Basin (600-1200 AD), the Anasazi cliff dwellers of the Colorado Plateau (500-1300 AD), the Aztecs of Mexico (1100-1550 AD) and the Incas of Peru-Bolivia-Chile (1400-1550 AD).