A nation, and later a tribe, of American Indians that spoke an Algonquian language (Miami-Illinois). In the 1670s, the Miami formed a nation of six tribes (including the Atchatchakangouen, Kilatika, Mengakonkia, Peikokia, Piankashaw, and Wea tribes) that lived in southern Wisconsin and northern Illinois. The Miami became a tribe in the early 1700s, when several of its constituent groups merged or disappeared and the Miami moved to the upper regions of the Wabash and Maumee river systems in eastern Indiana. Today, the Miami tribe maintains its headquarters in Miami, Oklahoma.