Page "History of England" Paragraph 27

The first recorded Viking attack in Britain was in 793 at Lindisfarne monastery as given by the Anglo-Saxon Chronicle.

However, by then the Vikings were almost certainly well established in Orkney and Shetland, and it is probable that many other non-recorded raids occurred before this.

Records do show the first Viking attack on Iona taking place in 794.

The arrival of the Vikings, in particular the Danish Great Heathen Army, upset the political and social geography of Britain and Ireland.

Alfred the Great's victory at Edington in 878 stemmed the Danish attack ; however, by then Northumbria had devolved into Bernicia and a Viking kingdom, Mercia had been split down the middle, and East Anglia ceased to exist as an Anglo-Saxon polity.

The Vikings had similar effects on the various kingdoms of the Scots, Picts and ( to a lesser extent ) Welsh.

Certainly in North Britain the Vikings were one reason behind the formation of the Kingdom of Alba, which eventually evolved into Scotland.