Estralis, Estrayls, Estrayles, Estreiles
In some versions of the legend, it is the birthplace of Sir Tristan. In other versions, it is the location of a fountain or spring with magical healing properties.
Estrales is believed to be a fictional place, and there is no clear consensus on where it is supposed to be located.
In The Knight of the Parrot there is a Duchess of Estrales who loved Arthur.
Source
Le Chevalier du Papegau | Late 14th century or early 15th century