Polish-Lithuanian Commonwealth

The Polish-Lithuanian Commonwealth, actually called the "Republic of the Two Nations" or "Commonwealth of Both Nations", was a federal monarchic republic that was formed in 1569 by the Kingdom of Poland and the Grand Duchy of Lithuania, and lasted until its final partition in 1795.

( See http://en.wikipedia.org/wiki/Polish-Lithuanian_Commonwealth)

The Commonwealth at its greatest extent (ca. 1630)