Serfs are the dominated class under Feudalism. Feudalism was a social and economic system that was dominant in medieval Europe from the 9th to the 15th century. Under feudalism, a lord or a monarch granted land to vassals in exchange for their loyalty and military service. The vassals were usually knights or nobles who had their own vassals, and the lowest class in this social hierarchy were the serfs, who were tied to the land and had to work for their lord or vassal in exchange for protection and a portion of the crops they produced. The serfs were not slaves, but they were not free either, as they were bound to the land and their lord. They had limited rights and were unable to leave the land without permission. Feudalism was gradually replaced by other economic and social systems such as capitalism and socialism, which emerged in the modern era.