Culen, who bore a Scandinavian name and byname Ring (Old Norse Hringr = ring-giver), should have been heir to the Scottish king Dub under the alternating system of succession, but he was not given the sub-kingship of Strathclyde in the usual pattern. This may have underlain his challenge to Dub, initially unsuccessfully at Duncrub (965), but later driving him into Moray to be slain at Forres (966). Culen himself was subsequently slain by Riderch, son of Donald of Strathclyde, who had almost certainly excluded him from that sub-kingship; it is alleged that he had carried off Riderch's daughter. On Culen's death, the Scottish kingship swung back to the house of Constantine I in Kenneth II, who maintained the feud by slaying Culen's brother Olaf (977).
From The Kings and Queens of Britain in Oxford Reference.
Subjects: British History.