Kenneth MacAlpin's mother was probably descended from the royal house of Fortriu and his great-grand uncle, Alpín, had reigned as kings of the Picts until deposed by Óengus in 728.
Two such sources, The Prophecy of Berchán and De instructione principis, note that in 841 MacAlpin attacked the remnants of the Pictish army and defeated them.
Faced with a recently victorious MacAlpin in the south and a devastated army in the north, Drest, as well as all claimants to the Pictish throne from the seven royal houses attended this meeting at Scone.
It is Giraldus Cambrensis in De Instructione Principis who recounts how a great banquet was held at Scone, and the Pictish king and his nobles were plied with drinks and became quite drunk.
Following this event, Kenneth MacAlpin became king of both realms, harking back to his maternal ancestry to establish his claim to the throne of Pictavia and inheriting Dál Riada from his father.