Deed from the Five Nations to the King, of their Beaver Hunting Ground, more commonly known as the Nanfan Treaty, was an agreement made between the representatives of the Iroquois Confederacy with John Nanfan, the acting colonial governor of New York, on behalf of The Crown. The treaty was conducted in Albany, New York, on July 19, 1701, and amended by both parties on September 14, 1726.

The Five Nations (which became the 'Six Nations' after 1720) granted "after mature deliberation out of a deep sense of the many Royal favours extended to us by the present great Monarch of England King William the Third" the title to a vast area of land, covering significant portions of the present-day Midwestern United States and southern Ontario that they had claimed as a hunting ground, as far west as 'Quadoge' (now Chicago), by right of conquest during the later Beaver Wars of the 17th century.As the vast majority of the Beaver Hunting Grounds described in the Nanfan Treaty were also claimed by New France or its Algonquian Indian allies, the French did not recognize the treaty (it did recognize Iroquois suzerainty to the British crown in the 1713 Treaty of Utrecht) and the English made no real attempt to settle these parts for the time being. In the amended agreement 25 years later, the strip of land 60 miles wide adjoining Lakes Erie and Ontario, starting at Sandusky Creek, was reserved for continued Six Nations occupation and use, with the permission of its owner under the 1701 agreement, the King of Great Britain.

A copy of the treaty, containing the totem images of more than a dozen Iroquois chiefs, is part of the collections of the British National Archives.

The Iroquois ( or ) or Haudenosaunee (; "People of the Longhouse") are an Iroquoian indigenous confederacy in northeast North America. They were known during the colonial years to the French as the Iroquois League, and later as the Iroquois Confederacy. The English called them the Five Nations, comprising the Mohawk, Oneida, Onondaga, Cayuga, and Seneca (listed geographically from east to west). After 1722, the Iroquoian-speaking Tuscarora people from the southeast were accepted into the confederacy, which became known as the Six Nations.

The founders of the Iroquois League are traditionally held to be Deganawidah the Great Peacemaker, Hiawatha, and Jigonsaseh the Mother of Nations. For nearly 200 years, the Iroquois were a powerful factor in North American colonial policy. At its peak around 1700, Iroquois power extended from what is today New York State, north into present-day Canada, west along the Great Lakes and south on both sides of the Allegheny mountains into present-day Virginia and Kentucky and into the Ohio Valley.

The St. Lawrence Iroquoians, Wyandot (Huron), Erie, and Susquehannock, all independent peoples known to the European colonists, also spoke Iroquoian languages. They are considered Iroquoian in a larger cultural sense, all being descended from the Proto-Iroquoian people and language. Historically, however, they were competitors and enemies of the Iroquois League nations. Cherokee is also an Iroquoian language.

In 2010, more than 45,000 enrolled Six Nations people lived in Canada, and over 81,000 in the United States.