Interracial marriage
From AD 839, Viking Varangian mercenaries who were in the service of the Byzantine Empire, notably Harald Sigurdsson, campaigned in North Africa, Jerusalem and other places in the Middle East during the Byzantine-Arab Wars. They interbred with the local population as spoils of warfare or through eventual settling with many Scandinavian Viking men taking Arab or Anatolian women as wives. There is archaeological evidence the Vikings had established contact with the city of Baghdad, at the time the center of the Islamic Empire, and connected with the populace there. Regularly plying the Volga with their trade goods (furs, tusks, seal fat, seal boats and notably female slaves; the one period in the history of the slave-trade when females were priced higher than males), the Vikings were active in the Arab slave trade at the time. These slaves, most often Europeans that were captured from the coasts of Europe or during war periods, and sold to Arabic traders in Al-Andalus and the Emirate of Sicily.
History of Finland
Contact between Sweden and what is now Finland was considerable even during pre-Christian times; the Vikings were known to the Finns due to their participation in both commerce and plundering. There is possible evidence of Viking settlement in the Finnish mainland. The Åland Islands probably had Swedish settlement during the Viking Period. However, some scholars claim that the archipelago was deserted during the 11th century.
According to the archaeological finds, Christianity gained a foothold in Finland during the 11th century. According to the very few written documents that have survived, the church in Finland was still in its early development in the 12th century. Later medieval legends from late 13th century describe Swedish attempts to conquer and Christianize Finland sometime in the mid-1150s.