In 1652, Sir Thomas Urquhart of Cromarty wrote the "True Pedigree and Lineal Descent of the most Ancient and Honourable Family of Urquhart, in the House of Cromarty, from the Creation of the World until the year of God 1652."
He solemnly stated that in the 8th century of the Christian era Vocompos, head of the House of Cromarty, "had to his second brother one named Phorbas Urquhart, and Hugh to the third; of whom some few hundred years after that, the names of Forbes and Mackay had their beginning."
In his own genealogy, Sir Thomas Urquhart described himself as the 143rd in direct descent from Adam and Eve.
"We laugh at Sir Thomas's crazy genealogies," wrote Rev. Angus Mackay (1906), "but note the fact that he records the MacKays, the Urquharts and the Forbes were of the same stock."
Fifteen years later, in 1667, William Forbes edited and drew up a preface for the "House of Forbes," compiled by Matthew Lumsden in 1580. In this preface, he says Ochonochar, an Irish Lord who came over to Scotland, had a son Ochonochar, and that this second Ochonochar had three sons, who became the respective progenitors of the families of Forbes, Urquhart and MacKay.
Sir Robert Gordon of Gordonston, son of Alexander, 11th Earl of Sutherland, wrote a history about the earldom of Sutherland about 1630 which includes much information about the MacKays and other clans. Sir Robert is notoriously unjust to any family not on friendly terms with the Sutherlands, and particularly so to the MacKays whom he bastardizes with great freedom and hostile spirit. However, he states that the Forbes and MacKays had a common origin.
Other writers also state that there was an original connection between the Strathnaver MacKays (extreme north of Scotland) and the Forbeses in the old provinces of Moray and Buchan. Sir Thomas Urquhart, says Rev. Angus Mackay, was on intimate terms with the MacKays who, like himself, were staunch supporters of the two kings Charles. Historical documents indicate a warm friendship existed between the clans Forbes, Urquhart and MacKay for centuries.
Documents written before 1715 give evidence of a close friendship between the families of Forbes and MacKay who lived far apart; hence, strongly confirm the common tradition that these clans are of kindred stock.