Answer: The extinction of the slave-owning system and the penetration of barbarian tribes.
Step-by-step explanation:
The fall of the Western Roman Empire, whose economy was largely based on slave labor, gradually led to the disappearance of the slave-owning system's ancient heritage. In such circumstances, a new economic and social order emerged in Europe called the feudal system. The Germans and the Slavs played an increasing role in Europe after the fall of the Western Roman Empire. They permanently inhabit certain parts of the European continent. Since the Roman Empire was no longer the dominant factor in Europe, these peoples were the bearers of the feudal system's ideas.