Dogfael was the eighth son of Cunedda Wledig (the Imperator). When the Irish became dominant in North Wales, he travelled, with his family, from their home in Manau Gododdin (on the Forth) to expel them. Dogfael was then given the area around Rhuthin as a reward and here he set up the kingdom named after him. He probably ruled as a sub-king under his brother, King Einion Yrth (the Impetuous) of Gwynedd.

It is unclear for how long his descendants continued to use the title of "King", but they appear to have enjoyed a certain amount of power in the area, if not a great deal, probably into the early eighth century. He was succeeded by his son Elno and, later, his grandson, Glas.