The Five Nations, also called the Iroquois Confederacy, originally consisted of the Cayuga, Mohawk, Oneida, Onondaga and Seneca nations, all inhabiting land in the present-day states of New York and Pennsylvania. In 1722, the Tuscarora tribe joined the Confederacy after being displaced from the Carolinas, creating the Six Nations.
The Iroquois Confederacy dates back to at least the 15th century, and was formed by Deganawida "The Peacemaker" as a way to keep the five original nations from warring against one another by providing structures for discussion and conflict resolution between the tribes. Another goal of the confederacy was to shelter those in need, accepting the lost and displaced peoples that found themselves in the region due to the expansion of European colonization.
The Iroquois Confederacy eventually fell during the Revolutionary War. The proximity of the tribes to the conflict between the British and the colonists meant they could not say completely uninvolved, but the nations disagreed on who they should support. Neither the British nor the Americans had been particularly good to the native tribes, and each side promised various things in exchange for support. Eventually, the Oneida and Tuscarora supported the colonists, while the remaining four tribes sided with the British.
While the Iroquois Confederacy was never again a powerful political force in the region, the spirit of the Nations lives on. As of 2010, approximately 125,000 people of Native American descent are enrolled in the Six Nations, with around one-third living in Canada.