Under the feudal system, who owned the land (known as a fief) provided to a knight in exchange for money or loyalty
caliph
serf
vassal
lord

Lord

Feudalism was a blend of judicial and martial practices in ancient Europe that prospered among the 9th and 15th centuries. Army, cultural, and administrative procedures all developed the feudal system, in which land was substituted for work. In a feudal system, a farmer or craftsman recognized as a vassal acquired a piece of land in the record for assisting a lord or master, particularly during times of war.

a.   it resulted in widespread unemployment.

troy donahue,   i think.