Germanic successor States
Although some of the Roman Empire lived, many of the germanic people took over as the western part fell. The kingdoms of the Germanic people came to play and started to form from various tribes like the Visigoths and Ostrogoths. These tribes had the power to take over the parts of the Roman Empire but they could not sustain due to lack of resources.
More Germanic rise
The franks, another member of the Germanic people, came together and made great development in the Western Europe with their social influence. As the franks did not have a long lived empire they still had better techniques. The franks had more agricultural resources having them focus on the lower countries, also they had believed in the feudal system which worked very well for them.