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 raid warfare and tactics
In Northern Europe at the start of the 8th century, Vikings began raiding coasts of the British Isles across the sea from Scandinavia, particularly monasteries, which carried a great deal of valuable treasures. The first known raid was on the Holy Island of Lindisfarne off the English coast in 793. This raid was also the first one that made a lasting impact on the British Isles and made the Anglo-Saxons aware of the Viking threat. A primary source from the raid on Lindisfarne states that there "were immense flashes of lightning, and fiery dragons were seen flying in the air". These raids continued for the entirety of the Viking Age. These initial raids had a religious implication to them. Vikings would target monasteries along the coast, raid the towns for their booty, and destroy what was left. This caused mass fear amongst such monks, as they felt that it was punishment from God. There is also the complication of a lack of direct written sources about these raids from the Viking perspective. This leads to biased views of the raiders from Christians who were being attacked in their churches and lands . From their point of view, the Vikings were violent and evil heathens.