Feudalism is the political system that developed in Europe in the middle ages.
The Bubonic Plague was a desiest that made people sick and were carried by rats with fleas. They caused people to catch the desiese and die within a few days.
This occurred in Asia and started around 1200 and reduced alot of their population at that time.
This happened mostly because of famine. As the people were sick, they probably couldn't afford any food to keep themselves well.
This topic contributes to the Decline of Feudalism because so many people died that it made the Feudal structure fall off.
Peasants revolted in Europe and the peasants gained power because of the Feudal structure falling off. They maintained this power because so may people died that it was causing to make open spots for the peasants.