Five Nations, or Six Nations, the confederacy of Iroquois Indians that centered in what is now New York state. Five tribes of the Iroquoian language family—Cayuga, Mohawk, Oneida, Onondaga, and Seneca—formed a league about 1570, under the leadership of Dekanawida and Hiawatha. (Longfellow used Hiawatha's name, but not the events of his life, in his poem Hiawatha.) They were joined by Tuscarora groups from North Carolina, 1712–22, and thereafter were sometimes called the Six Nations. The Tuscaroras, however, never achieved full equality in the league.

The Iroquois were supplied with guns by the Dutch and, later, by the English, and conquered many Algonquian tribes. Siding with the English, the Five Nations was a strong factor in wars with the French. In the American Revolution the league lacked unity, and was badly defeated by the Americans. After the war the Mohawks and Cayugas, as well as some of the Senecas and Onondagas, settled in Canada.