Indeed, it's a little hard to believe modern historians with their new appraisal of the Vikings as a peaceful, enlightened traders bringing systems of law and democracy to the lands they settled.
The Viking raids on Britain began in 789, when three ships from Hordaland raided the Isle of Portland on the southern coast of Wessex. Further raids sacked the monasteries at Lindisfarne and Iona in 793 and 795 respectively, after which the Vikings traumatized the coasts of England and Scotland for nearly a hundred years.
It was then that they began to settle, starting in 866, when Norse armies captured York, one of the two major cities in England. They soon had Northumbria, Yorkshire and East Anglia under their sway, holding onto their territories until 937 when Erik Bloodaxe, the last Norse King of York was defeated at the Battle of Brunanburh.