WordNet (r) 3.0 (2006):

Iroquois League
    n 1: a league of Iroquois tribes including originally the
         Mohawk, Oneida, Onondaga, Cayuga and Seneca (the Five
         Nations); after 1722 they were joined by the Tuscarora (the
         Six Nations) [syn: Iroquois League, League of Iroquois,
         Five Nations, Six Nations]