A confederation (also known as a confederacy or league) is a political union of sovereign states united for purposes of common action. Confederations include:
Includes confederations of confederations:
The Ancient Greeks formed many Leagues which often acted as confederations and alliances usually to combat a common enemy, These polities would often be known as symmachia and koinon.
A supranational union is a supranational polity which lies somewhere between a confederation that is an association of sovereign states and a federation that is a single sovereign state.