The noble king of Karahes (Carhaix) and the father of Kahedins and Isolde of the White Hands (Iseult) in Eilhart’s Tristrant.
He refused to marry his daughter to Count Riole of Nantes, so Riole attacked him in revenge. Karahes was besieged and would have fallen if not for the timely arrival of Tristan, who defeated Riole, befriended Kahedins, and married Isolde.
He is represented in Gottfried’s Tristan as the similar sounding Jovelin, and is replaced in later Tristan legends by Hoel.
Source
Tristrant | Eilhart von Oberge, 1170–1190