The Feudal system, which was based on an economic relationship between wealthy noblemen (land-owners) and working peasantry (who paid land-owners a fee). It disappeared for the most part around 1500 because (1) the armies of noblemen were replaced by armies of professional fighters or mercenaries and (2) the Black Death, a European plague that killed between 75 and 200 million people, reduced noblemen's ability to govern the lower classes.
