It wasn't until Charlemagne united most of Gaul and created the Frankish Kingdom that some semblance of peace was restored, ushering in the Middle Ages and the return of economic growth and cultural development.
As an aside, everything I read and was taught about the Dark Ages, Middle Ages, and the Renaissance back in my day was deeply intriguing and rich in wisdom and knowledge. It saddens me greatly if it's all been whitewashed down to "Dark Ages wrongspeak, Early Middle Ages rightspeak" and "Middle Ages backwards, Renaissance forwards" today because that is so grossly worthless.