The exact relationship of Sweden to Finland in the twelfth century is not fully understood, as it is based rather on legend and tradition than on historical documents. At this time the Swedish kingdom had been established and in the middle of the twelfth century the throne was occupied by King Erik, a Christian who gave his allegiance to the Roman Church. To the east, the semi-independent state of Novgorod, founded by Vikings in the ninth century and linked to Kiev, was a centre which had commercial ties with the Baltic region and was also a base for a powerful military force. Finland was a buffer zone between the rival powers of Sweden and Novgorod and also came under pressure from the Baltic Germans, who penetrated into the lands south of the Gulf of Finland. The Finns, unlike their powerful neighbours, had not at this time established a state of their own. They were divided between the three main groups – the Suomalaiset, the Hämäläiset and the Karjalaiset who were often in conflict amongst themselves.

The legends tell of a crusade, led by King Erik of Sweden (accompanied by Bishop Henry of Uppsala) in 1155. Henry was an Englishman, originally a monk from Bury St Edmunds, one of three English clerics who had an influence on Finland at this time. The others were Nicholas Breakspear, who was later the first English Pope, and Bishop Thomas, who subdued the Hämäläiset in the early thirteenth century.