phantom power
phantom power
The Vikings was as good traders as they was warriors - and if it suits them - they could plunder at one place - and then sell the proceeds at another place - to earn some extra money - who gave them power back home.... Who in time also was given them more people who wanted to be on the "winning team" and therefore gave them more ability to go plunder and pillage the rest of europe 
And for a few centuries it was enough to make people scared about the vikings.. For the most part - the vikings even if its trading role was able to fetch some decent deals - the other side seldom was willing to risk getting hurt because they tried to bust a deal on wrong premisses.... Not when the other side had enough weapons for a small army
I'm not sure if History channel is the best channel (so to speak) about vikings - they often enlarge the warrior part - to the extreme sometimes - and cut out the part where the vikings was rather peacefully and was doing what people have doing in scandinavia for eons - living their life as best they was able to do... But you tube have tones of information about vikings - even from the point of trading over large distances. Specially BBC have some of the best out there... And of course you could allways try to pick up a book about the vikings - it is not excactly few books out there who is written about the vikings
Diclotican