Polish-Lithuanian Commonwealth

The time when Poland was actually strong.

1569-1795 (holy shit the polish-lithuanian commonwealth existed for more than 2 centuries)
First Partition - 1772 by Russia, Prussia and Austria
Second Partition - 1793 by Russia and Prussia
Third and final partition - 1795 by Russia, Prussia and Austria. The end of the Polish-Lithuanian Commonwealth's reign.

The Polish-Lithuanian Commonwealth almost beat the shit out of Russia by occupying the capital, Moscow for a bit before getting fucked by the Russian Military.