Dekanawida, born near the Bay of Quinte in southwestern Ontario, founded the Iroquois, or Five Nations Confederacy. A Mohawk Sachem called Hahyonhwatha (Hiawatha) acted as his spokesman. There had been too much bloodshed among the Iroquois; it had to stop, said Dekanawida. To ensure a lasting peace he proposed the five Iroquoian-speaking nations (Mohawk, Onondaga, Seneca, Cayuga, and Oneida) unite in a confederacy bound together with a formal "constitution."

According to tradition, Dekanawida and Hahyonhwatha needed 40 years to persuade all five nations to ratify the constitution known as Gayanashagowa, or Great Binding Law. Some historians estimate the final ratification may have taken place as early as August 31, 1142 A.D. They base their estimate partly on the date of a solar eclipse that according to Iroquois oral tradition occurred during the ratification ceremony. Astronomers say an eclipse was visible in the area where the ceremony took place on August 31, 1142. Gayanashagowa is codified in a series of wampum belts (strings of white and black shells woven into belts) that are now held by the Onondaga Nation. It defines the functions of the Great Iroquois Council and the way nations may resolve disputes and live in peace with each other.

Dekanawida designed his Great Binding Law with checks and balances that also ensured every man and woman had a say in tribal affairs. The powers of the War Chiefs balanced those of the Sachems (Civil Chiefs). The Clan Mothers chose Sachems and War Chiefs, and could replace them if they did not govern wisely. If the Clan Mothers failed to remove a bad Sachem or War Chief, either the women's or the men's council had the power to remove him and compel the Clan Mothers to select another man for the position. Every official, even the members of the Great Council, was subject to this law of removal.

The Iroquois Constitution played a part in many aspects of people's lives. It established women's and men's councils. It forbade marriage between members of the same clan. It stated how a person could be adopted into a nation and how a person could give up his or her membership in a nation. It protected each nation's right to hold religious ceremonies. The constitution also included sections on international affairs, outlining how and when war could be declared on foreign nations. It set out procedures by which peace could be made or war avoided.

The Great Binding Law proved so efficient in maintaining peace that it served as a template for the men who drafted the American Constitution as well as diplomats meeting to devise a United Nations Charter after the Second World War.