Saga
The Orkneyinga Saga says that a dispute between Thorfinn Sigurdsson and Karl Hundason began when Karl Hundason became "King of Scots" and claimed Caithness. According to the Orkneyinga Saga, in the war which followed, Thorfinn defeated Karl in a sea-battle off Deerness at the east end of the Orkney Mainland. Then Karl's nephew Mutatan or Muddan, appointed to rule Caithness for him, was killed at Thurso by Thorkel the Fosterer. Finally, a great battle at Tarbat Ness on the south side of the Dornoch Firth ended with Karl defeated and fugitive or dead. Thorfinn, the saga says, then marched south through Scotland as far as Fife, burning and plundering as he passed. A later note in the saga claims that Thorfinn won nine Scottish earldoms.
Whoever Karl son of Hundi may have been, it is thought that the saga is reporting a local conflict, perhaps with a Scots ruler of Moray or Ross:
he whole narrative is consistent with the idea that the struggle of Thorfinn and Karl is a continuation of that which had been waged since the ninth century by the Orkney earls, notably Sigurd Rognvald's son, Ljot, and Sigurd the Stout, against the princes or mormaers of Moray, Sutherland, Ross, and Argyll, and that, in fine, Malcolm and Karl were mormaers of one of these four provinces.
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