Which group was legally bound to the land they worked and required permission to leave?

The group that was legally bound to the land they worked and required permission to leave were serfs. Serfdom was a system that existed primarily in medieval Europe, where serfs were peasants who were tied to a specific piece of land and were obligated to work that land. They did not have the freedom to leave without their lord's consent, and their rights were significantly restricted compared to free individuals. This system was characterized by a series of obligations and duties towards the landowners, who provided them with protection and allowed them to work a portion of the land for their subsistence. The serfdom structure was an essential aspect of the feudal system, which dominated European society during the Middle Ages.