This article is from the Nordic countries FAQ, by Antti Lahelma and Johan Olofsson, with numerous contributions by others.
Western Scandinavia 1066-1319
Denmark and Norway are separate kingdoms. Christian faith is
established. Denmark is heavily engaged along the southern and eastern
shores af the Baltic Sea competing with Slavic Viking-like tribes and
later with Germans. The Germans grow in strength and come through the
Hanseatic League to dominate both the Baltic and the North Seas.
Eastern Scandinavia 1164-1319
Christian faith is established. Trade through Russia is no longer
possible. Agriculture increase in importance. Finland and Norrland is
incorporated in the Swedish realm (the question of when Götaland was
united with Svealand is complicated). The Hanseatic League compete
successfully with the Guthnish and Swedish traders. The League
establish Visby on Gotland as a major Hanseatic town.
Western & Eastern Scandinavia 1319-1521/1536
The Hanseatic League dominates all of Norden. The modern feudalism has
led to splitted realms both in Sweden (1310-19) and Denmark (1320-40)
and is countered by centralistic tendencies by king Magnus Eriksson of
Sweden, King Valdemar Atterdag of Denmark, and his daughter Queen
Margrete of Norway. The high aristocracy does of course obstruct. The
kingdoms are several times united in personal unions.
Danish kings struggle with Swedish magnates over the relation to
Germany. The Swedes (and Norwegians?) prioritize trade, the kings want
to fight first and trade then.
 
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