Bolesław III of Masovia
Polish prince member of the House of Piast, Duke of Płock since 1336 (under regency until 1340), ruler over Wizna and Sochaczew since 1345, formally a vassal of the Kingdom of Bohemia during all his reign (–)
Polish prince member of the House of Piast, Duke of Płock since 1336 (under regency until 1340), ruler over Wizna and Sochaczew since 1345, formally a vassal of the Kingdom of Bohemia during all his reign (–)