Kings ruled over kingdoms but, in reality, their power was mostly symbolic. They had a little control over the real centers of power, which was the fiefdoms. Fiefs were large estates given by kings to their vassals in exchange for loyalty, men and other services. Vassals were noble lords who ruled over their fiefs and wielded the real political power, military might and economic resources. Therefore, the power structure was decentralized and the authority was divided between the king and his vassals.