The Welsh Triads (Welsh, "Trioedd Ynys Prydein") is used to describe any of the related Medieval collection of groupings of three that preserve a major portion of Welsh folklore and Welsh literature. The Welsh Triads include references to King Arthur, Rhydderch Hael, and even undeniably historical personages such as Alan IV, Duke of Brittany,who is called Alan Ffyrgan.

The triad originated amongst the Welsh bards or poets as a mnemonic aid in composing their poems and stories, which later became a rhetorical device of Welsh literature. The Medieval Welsh tale, "Culhwch and Olwen" is distinguished by its use of triads.

The earliest surviving collection of the Welsh Triads is bound in the manuscript Peniarth 16, now at the National Library of Wales, which has been dated to the third quarter of the 13th century and containing 46 of the 86 triads edited by Rachel Bromwich. Other important manuscripts include Peniarth 45 (written about 1275), and the pair White book of Rhydderch (Welsh: Llyfr Gwyn Rhydderch) and Red Book of Hergest (Welsh: Llyfr Coch Hergest), which share a comment version clearly different from the version behind the collections in the Peniarth manuscripts.

Bibliography

• Rachel Bromwich, editor and translator. Trioedd Ynys Prydein: The Welsh Triads. Cardiff: University of Wales Press, 1978. ISBN 0-7083-0690-X