Native Americans, also known as American Indians, Indians, Indigenous Americans and other terms, are the indigenous peoples of the United States.There are over 500 federally recognized tribes within the U.The ancestors of modern Native Americans arrived in what is now the United States at least 15,000 years ago, possibly much longer, from Asia through Beringia.
Expansion of European-American populations to the west after the American Revolution resulted in increasing pressure on Native American lands, warfare between the groups, and rising tensions. This resulted in the ethnic cleansing of many tribes, with the brutal, forced marches coming to be known as The Trail of Tears.
As American expansion reached into the West, settler and miner migrants came into increasing conflict with the Great Basin, Great Plains, and other Western tribes. Contemporary Native Americans have a unique relationship with the United States because they may be members of nations, tribes, or bands with sovereignty and treaty rights.
The differences in cultures between the established Native Americans and immigrant Europeans, as well as shifting alliances among different nations in times of war, caused extensive political tension, ethnic violence, and social disruption.
Even before the European settlement of what is now the United States, Native Americans suffered high fatalities from contact with European diseases spread throughout the Americas by the Spanish to which they had not yet acquired immunity.
By comparison, the indigenous peoples of Canada are generally known as First Nations.
It is not definitively known how or when the Native Americans first settled the Americas and the present-day United States.
Since the 1960s the self-determination movement has resulted in many changes to the lives of Native Americans.
Today, there are over five million Native Americans in the United States.
At the time of first contact, the indigenous cultures were quite different from those of the proto-industrial and mostly Christian immigrants.
Some of the Northeastern and Southwestern cultures in particular were matrilineal and operated on a more collective basis than the Europeans were familiar with.
The archaeological periods used are the classifications of archaeological periods and cultures established in Gordon Willey and Philip Phillips' 1958 book Method and Theory in American Archaeology.