I dont know why we are always entitled as "the vikings", they only lasted 400 years and they are mistakenly known as simple, raiding barbarians.
But I can understand, people want to pimp their own nations a bit for the sake of gathering enough interest from the crowd, and the Vikings did do a lot of impact on the international scenario, but I can see most of you out there knows a lot about other civilizations than just your own. In fact, I dont really understand how you think the Vikings would fit in Civ5 at all, because they gathered both economic and cultural growth (as well as spreading it) through war and raids - and I dont see the game mechanism awarding this ability to any civ.
Should we be implemented in Civ6, I dont think anybody in Scandinavia would mind being called "Norse", as the little documentation that exists states, we more or less originated from and existed as one people, connected through various bonds, alliances, marriages and cultural influences for 6000 years. We were not even close to being Vikings before 300 AD and we are certainly everything but Vikings today. The berserker is a myth - desperate young vikings, with nothing to loose and everything to win, combined with a deathwish to sit with Odin and Thor in the halls of Valhalla? Most likely.
But the longboat was very real and is a great idea for a unit.