The Guardian just reviewed the new Viking exhibition at the British Museum, emphasizing the commercial and political exploits of the eastern (Swedish) Vikings overland in what is now Russia and the Ukraine and Constantinople.

How the Vikings gave bling to the world

I made the following comment:

The Vikings - whether western (Norwegian/Icelandic) or eastern (Danish/Swedish) - were all ethnically and linguistically as good as identical. Their language only split into clearly distinguished eastern and western branches in the course of the Viking period itself, which was very brief - around 700 to 1066. And they were only late outrunners of the great Germanic explosion and migrations from around 400, which colonized eastern Europe and conquered central Europe, Rome and the various bits of the vast Roman Empire. And all these peoples had no great difficulty understanding each other - like Spanish and Italian speakers today, at worst. Anglo-Saxons, Vandals. Lombards, Franks, Normans, whatever.
And among the Vikings, the western lot went west and the eastern lot went east.
They conquered anything near water the way the Huns conquered anything near grass. They could sail any waters from great oceans to barely navigable rivers. And they did it with fighting squads as tightly-knit and aggressively inspired as any All Black rugby team.
What's more their politics were brutally fundamental. Power was the game, and they were brilliantly flexible tacticians. The spin-off Germanic (later Viking) states were maybe even more numerous and widespread than the spin-off states of Alexander's conquests, and that's saying something! Especially if you include (as you should) the late Roman Empire (Ravenna) and the Holy Roman Empire (Charlemagne)
In most cases, the fighting squad leveraged its power through vassals and fiefdoms - so a few Germans/Scandinavians could rule foreign populations who greatly outnumbered them - as in Rus and in Normandy. The Vikings probably took this art to its peak. And since power was most important, and loyalty and equality among the warrior elite (primus inter pares etc, Germanic common law) were the factors cementing the ruling caste together, all the rest mattered less - material culture, religion, even language. Becoming Normans, the Vikings adopted French ways, except when it came to power and the ethos of the Germanic nobility (feudalism) and even there their path had been prepared by the Germanic and equally pragmatic power-hungry Franks.
It's excellent that this more commercial, land-locked Viking surge is becoming more widely known.
Too bad our understanding of the whole impact of the Germanic explosion and expansion and its role in reshaping Europe and the Roman legacy is a mosaic that is still being laid. This is an important part of it, but late and very dependent on earlier developments.
Feudalism, for instance, is a fusion of the Roman imperial law (one gold coin is the equal of another) with the Germanic common law (communal sovereignty (so to say) and equality before the law (of "free" nationals of course).
The famous rune stone in Rök in Central Sweden (around 800, very early Viking period) is a monument to this more general sweep with its references to Theodoric in Ravenna. Makes a nice pendant to the Scandinavian (pre-Viking) elements in Beowulf. Sutton Hoo to Rök to the notorious runic graffiti on the Venetian lions from Constantinople.
For a lightning introduction to all this, visit two places when you come to Stockholm. One, the Historical Museum, and two, the burial mounds and museum at Old Uppsala.