What impact did german invasions have on the former roman empire?   

The German invasions had five consequences in the former Roman Empire:

The disruption of trade: Merchants faced land and sea invasions, which made their business collapse.The downfall of cities: The fall of the Roman Empire.Population shifts: Since Roman centers of trade collapsed, nobles retreated to rural areas and cities were abandoned.The decline of learning: Germanic invaders were illiterate and the only people left who were literate were Roman church officials.The loss of a common language: Since the german and roman population mixed, latin began to change and was no longer understood from region to region.

Finally, a new concept of government was born, in which family and personal ties were considered as the most important. As a result, small communities emerged, governed by unwritten laws and tradition.