Vikings in Iberia
Viking activity in the Iberian peninsula seems to have begun around the mid-ninth century as an extension of Viking raids on and establishment of bases in Frankia in the earlier ninth century. While connections between the Norse and Eastern Islamic lands were well-established, particularly involving the Rus') along the Volga and around the Caspian Sea, relations with the Western edge of Islam were more sporadic and haphazard. Although Vikings may have over-wintered in Iberia, no evidence has been found for trading or settlement. Indeed, the Iberian peninsula may not have offered particularly wealthy targets, in the ninth to tenth centuries. Sporadic raiding continued until the end of the Viking Age.
Naval warfare
In the 8th century the Vikings appeared, although their usual style was to appear quickly, plunder, and disappear, preferably attacking undefended locations. The Vikings raided places along the coastline of England and France, with the greatest threats being in England. They would raid monasteries for their wealth and lack of formidable defenders. They also utilized rivers and other auxiliary waterways to work their way inland in the eventual invasion of Britain. They wreaked havoc in Northumbria and Mercia and the rest of Anglia before being halted by Wessex. King Alfred the Great of England was able to stay the Viking invasions with a pivotal victory at the Battle of Edington. Alfred defeated Guthrum, establishing the boundaries of Danelaw in an 884 treaty. The effectiveness of Alfred's 'fleet' has been debated; Dr. Kenneth Harl has pointed out that as few as eleven ships were sent to combat the Vikings, only two of which were not beaten back or captured.