During the Middle Ages, the civilization that dominated in Western Europe was an unequal and feudal civilization.
The major social/governmental system in Europe during this time was the feudal system. This was the system in which a monarch ruled a country, but did not really have centralized control of that country. Instead, there were many lords who owed their allegiance to the monarch but who ruled their own territories fairly autonomously. This system continued on with those lords having lesser lords underneath them. This was a very unequal system with the masses at the bottom of the social pyramid having very little power while those at the top had a great deal of power and wealth.
Feudalism did not dominate all places and times in Middle Ages Europe, but it was the most prevalent type of civilization in this time and place.