I am wondering about this considering the pre-Clan bandit kingdoms along the LC/DC border and the history of the Marian Hegemony. To be honest the Marians seem to indicate it very well could be but part of what made the Vikings successful was the lack of any serious opposition in their home waters IIRC. I would have to dig but I am not sure how well their longboats did against other naval warships of the time.
I'm not aware of any significant naval power during the Viking period (late 8th century through mid 11th century) where the Vikings were most active in the North Sea or Atlantic. Later in the period, there were naval battles between different armadas from what we now call Denmark, England, and Norway. But those were basically Vikings fighting Vikings, even if one side had conquered/settled some kingdom(s) in the British Isles.
Some Vikings from Normandy (a part of what we now call France settled by Vikings from what we now call Norway and Denmark) made their way to the Mediterranean through the Straits of Gibraltar, all the way to Sicily. I don't think they encountered any naval powers, and there probably were none in that area so long after the fall of the Roman Empire and so deep into the Dark Ages.
There were obviously no naval powers farther west where the Norwegian Vikings settled the Isle of Man, Iceland, Greenland, and (briefly) Newfoundland.
Farther east, the Byzantine Empire and various Persian/Islamic powers had very significant navies. The Rus (Vikings from what we now call Sweden who started some of the major river cities in what we now call Russia and Ukraine) did have run-ins with the Byzantine navy in the Black Sea area during the 10th century and generally lost to the Byzantine's superior numbers and Greek fire. But some of the Rus, the so-called Varangians, also worked as Byzantine mercenaries and bodyguards, so it was not a simple, antagonistic relationship. I'm unaware of any warfare (naval or otherwise) between the Rus and Persian/Islamic powers, but they certainly traded a lot as silver dinars are found in large numbers in Norse graves in Sweden.
To sum up, the Vikings were successful raiders, traders, conquerors, and settlers partly because their longships gave them access to other seashores and rivers when none of their neighbors had such a capability. But when the Vikings did encounter a real naval power like the Byzantine Empire and tried to fight them on their terms in their waters, the Vikings lost. If you were to mimic this in the BattleTech universe, your "space Vikings" could best their Periphery neighbors at will but couldn't match a Successor State's capabilities.
I'd also argue that the Vikings succeeded because the kingdoms and peoples around them were in such disarray while the Norse were in the process of consolidation at home and nation-building abroad. After Charlemagne, there was no central authority covering a nation-sized territory anywhere in the British Isles, France, Germany, or Italy, but the states we now call Denmark, Norway, and Sweden all consolidated under one or two kings during this period. (In fact, for a couple decades, Denmark, England, Norway, and southern Sweden were all united under one Danish king's rule.) The Vikings faced little more than petty kingdoms over most of Northern and Western Europe, and it actually took Viking attacks, leadership, and/or influence to jump-start the development of the modern, large, nation-state in England, Ireland, France, and Russia. (Although it would still be centuries until these nations would be fully recognizable in their modern forms.) This doesn't really parallel the BattleTech universe. With the exception of House Marik during/after the Jihad, the Successor States have never plunged to the depths of what Western/Northern Europe did during the Dark Ages and shattered into many petty states. Each Successor State is more like a Byzantine Empire, weakened but still a centralized and powerful state in its own right after the fall of the Star League/Terran Hegemony (BattleTech's "Roman Empire").
They were also raiders- surprise, speed and violence of their assault would carry them through initially but they also quickly retreated off with their loot before heavier forces could respond. Later they went from raiding to conquering the territory from what I recall
Vikings often started with raiding (including taking slaves), moved up to extortion, and then graduated to conquering territories and peoples and extending their trade networks. This pattern repeated in Ireland, England, Northern France, and Russia/Ukraine.
- but politics, religion, technology and demographics had shifted.
The Vikings were change agents to these cultures, so they were responsible for a lot of the shifting. Their leaders centralized governments and militaries, required adoption of new religions, and introduced new trade. But the Vikings were limited in number, took native wives and husbands, and their descendants were often subsumed by the native, although changed, cultures over time.
Finally, I'd point out that the term "Viking" only applies to the subset of Scandinavian (called "Norse") culture from this time that undertook these overseas adventures. There were lots of Norse in Scandinavia that did not go "a-Viking". So if you're really interested in understanding the phenomenon, you have to study those societies in their totality. It would be like trying to understand 20th-century U.S. history by studying some biker gangs or military units in the United States from that time period.
Hope this helps.
