Nightbringer | The Arthurian Online Encyclopedia

Three Chief Steeds of the Island of Britain

Tall Black-Tinted, horse of Cynan Garrwyn; Eager Long Fore-Legs, horse of Cyhored, son of Cynan; and Red … Wolf-Tread, horse of Gilbert, son of Cadgyffro. The third horse is called Rudvreon Tuthvleid or Ruthir ehon tuth bleit in the Black Book version of Triad no. 52.

Red Book of Hergest | C. 1425
Text of the Mabinogion and Other Welsh Tales | John Rhys, 1887