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.
Vikings
A consequence of the available written sources, which may have coloured how the Viking age is perceived as a historical period, is that much more is known of the Vikings' activities in western Europe than in the East. One reason is that the cultures of north-eastern Europe at the time were non-literate, and did not produce a legacy of literature. Another is that the vast majority of written sources on Scandinavia in the Viking Age come from Iceland, a nation originally settled by Norwegian colonists. As a result, there is much more material from the Viking Age about Norway than Sweden, which apart from many runic inscriptions, has almost no written sources from the early Middle Ages.