Walt — Vikings were the same peoples who were not even on the awareness of Europeans from Roman times, in the early Dark Ages, and so on.
There has been some research done into just why the Vikings went raiding. Archaelogical evidence suggests a population explosion, bad farming conditions, and poor fisheries combined with weakness led to Viking expansion.
What your point misses is how WEAK other nations/peoples were around the Vikings. Much of Scotland, Ireland, England, Northern France, and more were both within easy reach of superior Viking technology (their superb long boats, with shallow drafts allowing navigation on almost any river) while the Viking homelands were unable to be raided in return (due to the Europeans inability to create navies for punitive expeditions).
Moreover, great swaths of lands gave huge opportunities for whatever Viking chieftan could indeed conquer them, and take the taxes as his tribute. The Saxon kings were too weak to fight off the Vikings. As was Charlemagne, and the Irish and Scottish kings, and so on. It was only with the Norman invasion that Vikings were kicked out of England, the Normans being better at heavy infantry, cavalry, and of course castle building, making Viking raids troublesome for the populace but unable to breach the Norman fortresses, from with lots of men at arms could sally forth and cut more lightly armed Vikings to pieces.
The lesson of the Vikings is that making oneself vulnerable to plunder and conquering … invites plunder and conquering. The Vikings were wold-beaters for about 300 years because they had technology (long boats) no one else had and the forces they faced were pretty weak. They could not continue to hold their great empires because like the Mongols, technology caught up to them and there were too few in an age when manpower was all-encompassing.
The reason why certain people get concentrated in a few areas is usually pretty simple: a confluence of wealth, technology, and so on. Dutch Masters like those of the Italian Renaissance are easily explained by both astonishing Merchant Wealth and the desire to compete with the nobility. File that under “duh.”
And contrary, the reason for rise and fall of empires and peoples is almost ALWAYS well understood, it’s merely that the lessons are so unpleasant that people shy away from the obvious.
Greece fell because they failed to unite against Philip and Alexander, disdained their use of cavalry, and did not have enough children to create a manpower advantage. the Hellenistic kingdoms fell because they both lacked manpower, and did not adapt to the flexible advantages of the Roman legions which could get around the pike-walls and come in from the sides or behind. Carthage fell because it did not have enough unity or manpower either, and could not match Rome in massive levy after massive levy. Rome fell when it ceased having enough native soldiers and depended on foreign mercenaries who soon became their conquerers. Spain fell when it ran out of soldiers and did not compete with a global navy. And so on.
Generally: not enough people, not adapting to new technology. Most simple things are hard to understand and even harder to do.
