According to the Highland manuscript believed to be written by one MacLauchlan, bearing the date 1467, and containing an account of the genealogies of Highland clans down to about the year 1450, which was accepted as authoritative by Skene in his Celtic Scotland, and believed to embody the common tradition of its time, the origin of the Davidsons is attributed to a certain Gilliecattan Mhor, chief of Clan Chattan in the time of David I. This personage, it is stated, had two sons, Muirich Mhor and Dhai Dhu. From the former of these was descended Clan Mhuirich or Macpherson, and from the latter Clan Dhai or Davidson. Sir Aeneas Macpherson, the historian of the clan of that name, states that both the Macphersons and the Davidsons were descended from Muirich, parson of Kingussie in the twelfth century.

The chiefs of the Davidsons are said to have been settled, in early times at Invernahavon, a small estate in Badenoch, at the junction of the Truim with the Spey, and when they emerge into history in 1370 or 1386 the holders of the name appear to have been of considerable number, and in close alliance with the Mackintoshes from whose forebears they claim descent.