[1][2][3] After Iolo Morganwg's death in 1826, his son Taliesin Williams set about collecting and publishing his unpublished manuscripts.

John Williams, alias "Ab Ithel", was among the first to take up the offer; he edited the two volumes now known as Barddas for the Welsh Manuscripts Society, which appeared in 1862 and 1874.

[4] Williams claimed the Barddas material was based on authentic ancient manuscripts originally compiled by the 16th-century antiquarian Llywelyn Siôn.

It discusses Iolo's elaborate philosophy and cosmology, which he claimed was the actual belief system of the ancient bards.

[6] The third section, "Wisdom", contains esoteric lore that may date from the 16th–17th centuries, though not from ancient druidic tradition as Iolo claims.