During Culhwch’s quest to win the hand of Olwen, he is given a series of seemingly impossible tasks by Olwen’s father, the giant Ysbaddaden. One of the tasks is to hunt the wild boar Twrch Trwyth, a ferocious and supernatural creature.
Culhwch set out on the hunt with his companions, and they encounter various adventures and challenges along the way. As they travel, they come to a ford guarded by a warrior named Cyledr Twll Dylluan, who is stationed at a place called Deu Gleddyf – which means “Two Swords” in Welsh, referring to Cyledr’s formidable fighting ability.
Cyledr challenges Culhwch and his companions to battle, and a fierce fight ensues. In the end, Culhwch’s cousin Arthur intervenes and defeats Cyledr in single combat. After defeating Cyledr, Culwch and his companions continue their hunt for Twrch Trwyth.
Note
– twll is Welsh, meaning deceit, fraud.
Source
Culhwch and Olwen | Late 11th century