By implication the Orkneyinga saga identifies him as such for he is given "dominion" over Orkney and Shetland by King Harald Finehair, although there is no concrete suggestion he ever held the title.

However, unable to constrain Danish raids on Orkney, he gave up the jarldom and returned to Norway, which "everyone thought was a huge joke".

[b] One of the main sources for the lives and times of these jarls is the Orkneyinga saga, which has been described as having "no parallel in the social and literary record of Scotland".

The last quarter of the saga is taken up with a lengthy tale of Jarl Rögnvald Kali Kolsson and Sweyn Asleifsson — indeed the oldest version ends with the latter's death in 1171.

[18][19] After the murder of Jarl Jon Haraldsson some sixty years later, Magnus, son of Gille Brigte became the first of the Scottish earls.

[7][20] alone 954–963[21][e] with Einar and Thorfinn to c. 1031[7][31] After the close of the Jarls' Saga on the death of Jon Haraldsson in 1230, the history of Orkney is "plunged into a darkness which is illuminated by very few written sources".

[42] Although successive jarls of Orkney were related, they each acquired the position by being personally appointed to the role by the Norwegian king; the jarldom was not inheritable.

The lack of haste with which a new title was granted by the Norwegians to Orkney has led to the suggestion that Magnus Jonsson may have had an heir who was a minor, but who died before 1330.

[51] Whatever the reason, about a decade after Magnus's death the title was granted to Maol Íosa, mormaer of Strathearn, a distant relative of Earl Gilbert.

[57] When James III of Scotland married Margaret of Denmark, her father, Christian I, king of the Kalmar Union, was unable to immediately provide a dowry.

As an immediate consequence, the diocese of Caithness was transferred from the Archdiocese of Niðaróss (Trondheim), in Norway, to that of St Andrews, in Scotland.

The peerage was created with "remainder to the heirs whatsoever of his body",[citation needed] meaning that the title can be passed on through both male and female lines.