No Native people affected the course of seventeenth- and eighteenth-century American history more than the Haudenosaunee, or Iroquois, of present-day upstate New York. Historians have been attempting to explain how and why ever since, and central to their explanations is the remarkable political and diplomatic structure, the League of the Iroquois. The League has fascinated us for hundreds of years. In the seventeenth century, this Native confederacy united the Five Iroquois Nations—the Mohawks, Oneidas, Onondagas, Cayugas, and Senecas—into something more than an alliance but something less than a single, monolithic polity.