The supposed reasons for the sudden appearance of the Vikings at the end of the 8th century are many and varied.
The overpopulation of their lands is one of the often-cited primary factors in the population explosion that occurred in Norway and Denmark in the course of the 7th to 8th centuries. In addition, the gradual establishment of a firm government in most of Western Europe, especially on the continent with the founding of the Carolingian Empire under Charlemagne, had resulted in a considerable increase in European trade, which led to increased opportunities for trade. piracy.