What role did barbarians play in the life of earlier medieval Europe?

The barbarians created new states during the collapse of the Western Roman Empire. its disintegration was due to the fragmentation within the country: this situation made it weak. In these states, the norms of Roman law were in force, the Roman political system was operating. This was due to the fact that at that time the order of succession to the throne was not determined. Power was vested in the sons of the ruler, however, representatives of the nobility could nominate their own candidate. The Kingdom of the Visigoths, the Kingdom of the Vandals and Alans, the Kingdom of the Burgundians, and the Kingdom of the Franks were formed.