Which class of people earned fine houses and lands to rule in exchange for their services

Feudalism was a system of land tenure according to which land was held in return for services. This system developed in Europe during the Middle Ages. Under the feudal system, the king was the owner of all the land. The king granted portions of land to nobles (vassals/barons/greater-tenants-in-chief) in return for military service. In the same way, these nobles granted land to lesser nobles (sub vassals/knights/tenants-in-chief) who in turn paid military services directly to their lord (noble) and indirectly to the king (noble's lord).