Credir bod storïwyr Celtaidd wedi crwydro Prydain a thu hwnt yn rhannu straeon er mwyn derbyn bwyd a lloches, cyn i’r chwedlau gael eu cofnodi ar ffurf ysgrifenedig. Lluniwyd Llyfr Gwyn Rhydderch yng nghanol y bedwaredd ganrif ar ddeg ac mae’n rhan o gasgliad trysorau’r Llyfrgell Genedlaethol.
It is thought that Celtic storytellers wandered Britain and beyond sharing stories for food and lodging before ending up in written form, with the Mabinogi being the oldest recorded prose of its kind. The White Book of Rhydderch was produced in the mid-fourteenth century and is part of the National Library's collection of treasures.