Three entries with the name Amangon.
Amagons, Amangons, Amaugon
A king in Arthur’s service in Renaut de Bâgé’s Le Bel Inconnu, probably from Chrétien’s Amauguin.
Amangon is also mentioned briefly in La Bataille de Loquifer and Les Merveilles de Rigomer.
Le Bel Inconnu | Renaut de Bâgé, 1185-1190
La Bataille de Loquifer | c. 1230
A wicked king who ravaged a collection of well fairies who lived in the Grail Kingdom, stealing their golden cups. Other knights followed his example. Afterwards, the kingdom became a waste land, and the Grail Castle was hidden.
Amangon had a son named Pecorins.
Fairies | Myths and Legends
The Elucidation | 13th century
He is also named as the ruler of the Land From Which No One Returns. This according to the Old French Le Chevalier as deus espées.
Meriadeuc or Le Chevalier aux Deux Éspées | c. 1225-1250