Question: When was the story by Lovecraft that the Xothic legend cycle is based on first published?
Sentence (from "Guinevere"): This story first appeared in Chrétien de Troyes's "Lancelot, the Knight of the Cart" and became a motif in Arthurian literature, starting with the Lancelot-Grail of the early 13th century and carrying through the Post-Vulgate Cycle and Thomas Malory's "Le Morte d'Arthur".
Relevant evidence: No