Confederacy

noun

1. An alliance.
2. A state where the sovereign constituent units delegate their authority to the centre. As opposed to a federation, where the central and regional governments are each equal and sovereign in their own sphere.
3. Specifically, an instance of a decentralized governing structure among the indigenous peoples of North America.

   "The Blackfoot, Iroquois, and Sioux peoples all were governed as confederacies. There were also multi-ethnic confederacies, such as the Iron Confederacy made up of the Plains Cree, Assiniboine, Stoney, and Saulteaux."