What threat did Europe face in the 700s

Vikings

Explanation:

Scandinavian people whose sailors raided Europe from the 700s through the 1100s.

Broke the last threads of unity in Charlemagne's empire.

the historians cited in the article all agree with one another about the cause of the civil war. despite coming from different backgrounds and cultures, the historians agree that slavery was the root cause of the civil war. the fact that all these historiansgenerally agree with one another makes their shared viewpoints more reliable and valid, especially because the historians have different backgrounds and all work for the well-respected institutions of howard university, clemson university, and the university of colorado.