From Civilization V Wiki
Hiawatha (or "Ayonwentah") is the legendary chief of the Onondaga Indians who, with the equally-legendary Chief Dekanawidah formed the Iroquois Confederacy. Little is known about Hiawatha the man; according to Iroquois tradition he taught the people agriculture, navigation, medicine, and the arts, using his great magic to conquer all of man's supernatural and natural enemies. Hiawatha is also believed to have been a skilled orator who through his honeyed words persuaded the five tribes − Cayugas, Onondagas, Oneidas, Senecas, and Mohawks − to form the Five Nations of the Iroquois.
What little the West knows about Hiawatha is usually seen through the prism of Henry Wadsworth Longfellow's remarkable epic poem, Song of Hiawatha.
Verdict of History
No verdict is possible on such a legendary figure. The only thing that can be said is that however it occurred, the alliance of the Five Nations proved to be long and remarkably sturdy, even in the face of ever-increasing pressure from the advancing Europeans to the east. Whoever built that alliance certainly did an outstanding job.