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.
Viking expansion
Our knowledge of Vikings in Iberia is mainly based on written accounts, many of which are much later than the events they purport to describe, and often also ambiguous about the origins or ethnicity of the raiders they mention. A little possible archaeological evidence has come to light, but research in this area is ongoing. Viking activity in the Iberian peninsula seems to have begun around the mid-ninth century as an extension of their raids on and establishment of bases in Frankia in the earlier ninth century, but although Vikings may have over-wintered there, there is as yet no evidence for trading or settlement.