How do you assess the importance of Viking campaigns for the history of Europe in the early Middle Ages?

Perhaps the assessment will be very ambiguous. After all, judge for yourself, on the one hand, all these raids simply devastated the peoples of Europe, brought ruin and grief, but if you look from the other side, their engagement in trade and exchange contributed to the establishment of trade relations between different parts of Europe, in addition, they contributed to the settlement unpopulated land. With the help of the Vikings, a number of local princes carried out a campaign in order to seize other lands. Also, the Vikings served with some Slavic princes.