The body of water between Egypt and Arabia.
The otherwordly realm where Arthur went to dwell with Morgan is placed near here in the fourteenth-century French chanson de geste poem Le Bâtard de Bouillon, “The bastard of Bouillon”.
In Wigalois the land of Jeraphin was next to the Red Sea.
Sources
Le Bâtard de Bouillon | 14th century
Wigalois | Wirnt von Grafenberg, early 13th century