The political system of the Middle Ages in Europe was based on interlocking connections between vassals and lords. These connection were based on loyalty for service or land.
The feudal systems revolved around the monarchy and the "god-given" right to rule. That lasted until the Black Plague hit and there was a shortage of serfs to work.
The king split his land into fiefs and utilized vassals to oversee them. They would in turn use serfs to work the land and pay taxes for that privilege.
