Feudalism refers to the political and military system that developed in Western Europe during the Middle Ages. Although it provided no strong central government, it served basic needs for order and protection.
The foundation upon which feudalism was based was the ownership and power over land. In the A.D. 400s, after Germanic tribes had conquered the West Roman Empire, the land was divided into many small realms or kingdoms, over which different tribes and clans had power. In the absence of the central and regional Roman governments, tribesmen were loyal only to their families and chiefs. Thus began the dark ages, a time during which invasions and small wars were constantly breaking out across Europe.
Feudalism developed to meet the needs of the time. It was becoming common practice for the owner (person in power over) of a particular realm to grant portions of his land to others in return for goods and/or services. However, the expansion of the Muslim Empire into Spain by the 700s threatened all of Western Europe. So many turned ownership of their land over to a powerful lord in return for protection. These people then still stayed on the land as tenants, ultimately becoming the peasants or "serfs" of the manorial system (see manorialism). The lord provided the protection by granting portions of his land to warriors who swore allegiance.
In this practice, the owner eventually came to be known as the lord. The person giving goods and services in return (the lords subject) was the vassal, while the land he received was called the fief. As development of the system progressed, some standards developed. When the lord granted the vassal his fief, the vassal then had to hire knights, the number depending on on the size of the fief (which ranged anywhere from a plot of land to an entire territory). In hiring knights, the vassals then took the role of the lord, granting land for service. The same then may have been done with the knights hired by the vassal. It was in this way that the hierarchical nature of feudalism developed, all based on the defense of the land. As we will see, the primary defensive factor was represented by the castle, which commanded the land. If the castle was held, then the land was held. And if the castle fell to a siege, then the land was lost to the enemy.