Final answer:
Feudalism is a system in which the crown divided land among nobles, and knights served those nobles in exchange for the use of some land.
Step-by-step explanation:
The system described in the question is known as feudalism. Feudalism was a social and economic system that emerged in medieval Europe. It involved the exchange of land for military service, with the king or lord granting land to nobles who, in turn, granted land to knights. The knights would then serve the nobles in battle and provide protection in exchange for the use of land.