Feudalism
Understand feudalism — the medieval European system of lords, vassals, and serfs that organized society around land, loyalty, and military obligation.
Feudalism was the dominant social and political system in medieval Western Europe from roughly the 9th to the 15th centuries. At its core was an exchange: a lord granted land (a fief) to a vassal in return for military service and loyalty. The vassal, in turn, might grant portions of his land to lesser vassals, creating a layered hierarchy that extended from kings down to the peasants who actually worked the soil.
The system emerged from the chaos following the collapse of the Carolingian Empire and the Viking, Magyar, and Muslim invasions of the 9th and 10th centuries. With no strong central government to provide security, local strongmen — lords with castles and armed retainers — became the effective government. Peasants surrendered their freedom in exchange for protection, becoming serfs bound to the land they farmed. The manor — a self-sufficient agricultural estate — became the basic economic unit.
Feudalism was never a clean, uniform system. It varied enormously by region and period, and medieval people didn't use the word (it was coined later by historians). But the core dynamic — political authority fragmented among local lords, sustained by personal bonds of loyalty and land grants — defined Western European society for centuries and left deep marks on European law, politics, and culture.