Viking raids a defensive struggle.
Documents show that the Viking raids were a defense struggle against the papacy’s attemt to conquer the North. They were primarily neither raids, trading, or adventure travels. Previous historiography has often used the old sources (mainly annals, yearbooks) either maliciously or foolishly to defame the Vikings. When “populus christianus” became the subject of the Vikings' attacks it was translated to that “the people” were attacked but the expression indicates that only church people (priests, monks, bishops, church executives) were the Vikings’ enemies.
There was a perception that the Vikings were pirates, but one pope correctly called Vikings "marines". Some historical writers want to ridicule the Vikings by attributing them an inordinate desire for wine and other alcoholic beverages as well as a promiscuous living. Nothing could be further from the truth (sorry, “Vikings” fans), this is a misreading of the source texts.
The Viking raids in the east was about the conservation of the ancient custom in the Nordic region. The Swedish influence in Russia (eg. = Swedish country, The swedes, called the Rus, from where the name “Russia” eventually came about) – politically, culturally, legally – was strong and prevented the Asian front from penetrating.
The papacy was striving for world domination. The papacy was Scandinavia's enemy already during the Migration Period. The papacy was behind the Frankish war campaigns against Lombards, Schwaber, Frisians and Saxons and they extended their campaign to the Nordic countries by the end of the 700's, which eventually made the vikings’ go to counterattack, thus the ‘raids’ start in various historical accounts.
The North could not withstand their defense in the long run. The christian “mission” won by the sword, “Gladius ecclesiae” (the sword of the church) in the pope’s own words. That is wasn’t a “spiritual sword” is made obvious in a letter from Gregorius VII to the danish King Sven, where he writes that King Sven should assist with his “heathen sword” against heathens.
The truth about what happend when the ancient custom finally was crushed and the catholic church established is explained in various places. With the sword Slavs, Danes, Norwegians, Swedes etc. were subdued. Popular uprisings in Sweden against the introduction of the new Christian custom was common. The large declines in Sweden during the conversion period was not because of the lingering paganism, but a consequence of the introduction of Christianity. The monasteries were great centers of oppression of the people. Vikings were tradesmen first and foremost, you had to confess to christianity in the now christian europe. A child can figure out the rest of the story.

