Viking, or Norseman, Member of the Scandinavian seafaring warriors who raided and colonized wide areas of Europe from the 9th to the 11th century. Overpopulation at home, ease of conquest abroad, and their extraordinary capacity as shipbuilders and sailors inspired their adventures. In 865 Vikings conquered East Anglia, Northumbria, and much of Mercia. Wessex under Alfred the Great made a truce in 878 that led to Danish control of much of England. Alfred defeated fresh Viking armies (892–899), and his son continued his reconquest, recovering lands in Mercia and East Anglia by 924; Viking Northumbria fell in 954. Renewed raids in 980 brought England into the empire of Canute, and it remained as such until 1042, when native rule was restored.The Vikings permanently affected English social structure, dialect, and names. In the western seas, Vikings had settled in Iceland by 900, whence they traveled to Greenland and North America. They invaded Ireland in 795, establishing kingdoms at Dublin, Limerick, and Waterford. The Battle of Clontarf (1014) ended the threat of Scandinavian rule. France suffered periodic Viking raids but no domination. In Russia Vikings briefly dominated Novgorod, Kiev, and other centres, but they were quickly absorbed by the Slav population. As traders they made commercial treaties with the Byzantines (912, 945), and they served as mercenaries in Constantinople. Viking activity ended in the 11th century.