Complex sentence: Two Siouan peoples were not part of the Seven Fires Council: the Assiniboine and Stoney, who lived to the north of the others and were instead members of Iron Confederacy with the Cree, traditional enemies of the Sioux.
Split into simpler sentences: Two Siouan peoples were not part of the Seven Fires Council: the Assiniboine and Stoney, who lived to the north of the others. They belonged to the Iron Confederacy with the Cree, traditional enemies of the Sioux.