According to historical tradition, the ruling dynasties of the Ulaid were either of the Ulaid population-group or the Cruthin. Medieval Irish genealogists traced the descent of the Ulaid from the legendary High King of Ireland, Rudraige mac Sithrigi. The Cruthin on the other hand is the Irish term for the Picts, and are stated as initially being the most powerful and numerous of the two groupings. The terms Ulaid and Cruthin in early sources referred to the Dál Fiatach and Dál nAraidi respectively, the most powerful dynasties of both groups.