According to Sir Thomas Malory, one of the four enchantresses, associates of Morgan Le Fay, who captured Lancelot. Her accomplices where the Queen of Northgalis, the Queen of Sorestan and the Queen of the Out Isles. They took him to Castle Chariot (Cart Castle), wishing him to choose one of them for his paramour.
The Vulgate version of this episode has only three kidnapers: Morgan, the Queen of Sorestan, and Sebile the enchantress.
From this and other evidence, I suspect Eastland to be identical with Sorestan; thus the Queen of Eastland is to be identified with the Queen of Sorestan. Incidentally, the reputations of the Queens of Eastland, Norgales, and the Out Isles as dames of magic seem to rest – as far as Malory is concerned – on their association with Morgan and on Lancelot’s assertion that they are all four “false enchantresses”.