A more sensible suggestion is that, assuming Magnuss right to Caithness was inherited from his mother, she was related to the last Earl John, who died in 1232, and whose rights would have been divided between his two heiresses.] .
There appears to be no surviving contemporary evidence concerning the grant of the earldom.
However, Balfour Paul refers to a charter "noted in an old Inventory of Oliphant writs, made about 1594, and preserved in the General Register House" which states that King Alexander II granted "the erledom of South Kaythnes" to "Magnus sone to Gylcryst sum tyme erle of Angus".
During the 10th century the province of Argyll was added, and in the 11th century Buchan separated from Mar, while Caithness was conquered by the Norwegians.
The earldom of Dunbar was a further creation of the early 11th century, although it was only called as such from the early 13th century.
A charter dated 1351 which confirmed the donation of "terram de Kenny" to Aberbrothoc by "Walterum filium Turpini" quotes a document witnessed by "Domino Magno filio Comitis Domino Anegus filio Comitis".
He was apparently installed as Earl of (part) Caithness.Gillbride was the first individual to be styled (in 1135) Earl of Angus and members of his family succeeded him in the title until the mid-13th century. The Pictish Chronicle names Conchar Mormaer of Angus as father of Fynebole Lady of Fettercairn, who murdered Kenneth II King of Scotland in 995 in revenge for the slaughter of her only son oat Dunsinane. The Chronicle of the Scots and Picts dated 1177 records that "Kynnath mac Malcolm" reigned for 24 years and 2 months, was killed "a suis hominibus in Fetherkern" through the treachery of "Finuele filie filie Cunthar comitis de Anguss" whose only son had been killed by the king.The Pictish Chronicle names Conchar Mormaer of Angus and father of Fynebole Lady of Fettercairn who murdered Kenneth II King of Scotland in 995 in revenge for the slaughter of her only son oat Dunsinane . "Alexander nepos regis Alexandri, Beth comes, Gospatricius Dolfini, Mallus comes, Madach comes, Rothri comes, Gartnach comes, Dufagan comes, Willelmus frater regine, Edwardus constabularius, Gospatricius filius Walthef, Ufieth Alfricus pincerna" witnessed the charter dated to [1114/15] under which "Alexanderrex Scottorum filius regis Malcolmi et regine Margerete et Sibilla regina Scottorum filia Henrici regis Anglie" reformed Scone Abbey, son of --- (-). David I King of Scotland granted protection to the clerics of Deer by undated charter witnessed by "Donchado comite de Fib et Malmori d Athotla et Ggillebrite comite d Engus et Ghgillcomded Mac Aed"] [--- of Dunbar, daughter of GOSPATRICK Earl & his wife ---.It was presumably after , the date of a charter under which Alexander II King of Scotland donated revenue from mills in Invernarn to the bishopric of Moray which was witnessed by "M comite de Anegus et Katania".Although the name of the witness is given only in abbreviated form, the reference to the county of Angus suggests that it must be Malcolm Earl of Angus who is shown above.It is assumed therefore that Earl Malcolm resigned Caithness, or his claims thereto, in favour of Magnus.