Well, I would argue that, at the height of their power, they were more powerful than all of western Europe and showed signs of that civilization thing (consolidation of power in the form of empires, a hereditary monarch who exercised central control, being a merchant/trading power instead of just military).
When they integrated themselves into Christian civilization, however, they had already declined. No one can claim that the Swedes, Danes, or Norwegians ever had as much influence in their post-Viking days as the English, French, Dutch, Spanish, Portuguese, Russians, or Germans (with Russians and Germans varying depending on the specific period). They are relegated to Poland status (important and influential, but falling behind the first place leaders). I'd argue it is their status as Norsemen that set them apart.