In the romance of the same name, when Alexander the Great conquered England, he made Betis king. Betis was accepted by the people, for the line of Brutus had become extinct, and Betis's brother Gaddifer was made King of Scotland.
When Betis had killed the magician Damart, he was given the new name of Perceforest. He founded the Knights of the Franc Palais and built a temple to the Supreme God. His son Bethides made an unfortunate marriage to Circe, who brought the Romans into Britain. They wiped out the Franc Palais, and Perceforest and Gaddifer went to the Isle of Life.
After the coming to Britain of Alan, the Grail Keeper, Gallafer, grandson of Gaddifer, accepted Christianity and went to preach to his ancestors who still lived on the Isle of Life. They were baptized, left the island and came to a place where there were five monuments waiting for them. There they died.