The audacity! Europeans had feudalism for... as long as I can remember! Who do those colonists think they are?
1569–1795
"The Union possessed features unique among contemporary states. Its political system was characterized by strict checks upon monarchical power. These checks were enacted by a legislature (sejm) controlled by the nobility (szlachta). This idiosyncratic system was a precursor to modern concepts of democracy, constitutional monarchy, and federation."