Something clearly happened to make Viking raids obsolete. If they were still necessary for the Norse people, and it was just a matter of their neighboring countries becoming so good at fighting them that Viking raids couldn't happen anymore, Scandinavia would have experienced massive poverty and famines and never have progressed. It can't have been improved climate conditions in Scandinavia either, if anything things got worse with the beginning of the Little Ice Age in the mid-13th century. The only other thing I can think of is technology, but could it have progressed so much in the 11th century?
So how come Scandinavia transitioned from a land populated by people that were seen by the rest of Europe as low-tech "savages" who had to plunder (even settle, in some cases) more fertile lands to survive, to a collection of "typical" Christian medieval kingdoms who had normal diplomatic relations with the rest of Europe? How did they manage (without raiding) to achieve a level of material comfort high enough that their society stopped being centered around war and raids, and why couldn't that happen during the Viking age?
Tl; dr: The Scandinavian expanded their settlement area further mainly in inland Scandinavia/ Jutland Peninsula after the 11th century.
As I cited before in Did the Nordic countries use to have a comparatively larger population back at the time of the vikings? If not how were they so often able to raid Britain?, scholars estimate that the population of medieval Scandinavia (here also including Denmark) might have more than doubled between ca. 800 and ca. 1300, based on the available evidence - place name of occupied/ abandoned farmsteads across Scandinavia. In other words, more and more farmsteads had begun to be built in hitherto unsettled area during and after the Viking Age.
So, you might wonder why some Scandinavians [especially their local magnates] prefer the raids out of their homeland to the consolidation of the settlement nearby. The logic behind their preference was probably the political economy for the chieftain in Viking Age Scandinavia, as I also summarized before in After a successful viking raid, how did all the riches change their life and what did they do with their new found wealth? As long as the majority of them found it easier and more convenient to go out for raids for external wealth like silver than to cultivate the land, the Viking raids continued. But if once the relative superiority of the laid was lost, the Viking raids gradually got out of trend.
So how come Scandinavia transitioned......to a collection of "typical" Christian medieval kingdoms who had normal diplomatic relations with the rest of Europe?
Kings in late Viking Age Scandinavia had a incentive to control further raids by the local magnates - the surplus gained by the raids might enable the latter [magnates] to give power/ wealth to gather larger flocks to overthrow them.
At least especially in Denmark and in Norway, the 'Civil War', that is to say, throne strife period in the 12th and 13th centuries (1131-57 in Denmark and 1130-1240 in Norway) also contributed greatly to the annihilation of the power as well as number of old local magnate family. The land property tend to get concentrated in the fewer powerful hands, such as a king, very powerful aristocrats like the Hvide Family in Sjælland, Eastern Denmark, those who knew how to utilize the church and its attached ideology and institutions. In other words, new Christian ideology and church institution also gave further room for the ruler to accumulate authority as well as wealth.
The expansion of the trade (and the ruler's patronage on such kind of trade) had also been consolidated after the Viking Age. To give an example, early 12th century Norwegian rulers seemed to simplify the taxation from the commercial fishery in northern Norway, thus encouraged fishermen to expand the export of the dried fish by way of Bergen, the hub of the commerce in western Norway as well as the royal power base.
Thus, a kind of chicken or egg first dilemma, but the intensified trade relationship between Scandinavia and neighboring areas like England also certainly favored the more-European styled kingdom also in Scandinavia.
The following previous post of mine might also be interesting: At What Point Were Vikings no Longer Considered Vikings, and Just Seen as Christian/Christianized Danes, Swedes, Norwegians, etc.?
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