Celys
A castle on the Celice river, from which the castle took its name.
It was ruled by King Lac, Erec’s father, until he was slain by his nephews. During the Grail Quest, Erec returned to the castle and killed his cousins. The castle’s residents swore fealty to Erec, their rightful lord.
Source
Post-Vulgate Queste del Saint Graal | 1230-1240