This came from the fact that in the early Middle Ages it seemed more feasible to pay your warriors with land than with money. Money was scarce and harder to use

This came from the fact that in the early Middle Ages it seemed more feasible to pay your warriors with land than with money. Money was scarce and harder to use in a collapsed economy. In the beginning, you had just the fighting men of your barbarian post-Roman kingdom. The barbarians had their military egalitarianism, but what remained from the Antiquity's culture perceived soldiers more like we do (as a specialized force and not as the societal elite). The warriors (which became knights) were supposed to hold the land on the condition of military service. But it gradually became hereditary. Over the centuries, holding the main form of capital in the society gave knights high position and tremendous clout. (Note that the other big landowner was the Church.)