confederacy

Short definition from Wiktionary

Noun

1. 1
   An alliance.
2. 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. 3
   Specifically, an instance of a decentralized governing structure among the indigenous peoples of North America.

Proper noun

1. 1
   The Confederate States of America, the collection of American states that seceded from the United States in 1860–61, and fought against the Union in the American Civil War.