Mathuédoï I, count of Poher

Out of the union of the Breton royal family and that of the Counts of Rennes and Nantes came Alain III the Great or Grand, surnamed le Poher, Duke of Brittany. At his death in 909, joint succession fell to his son-in-law Count Mathuedoi of Poher and his cousin Gurmhailion (Geoffrey) who was Count of Cornouailles. Mathuedoi renounced his claim and exiled himself to England, but his son Alain Barbe-tort (Red Beard), reclaimed the duchy around 970.