The book has been widely influential, giving rise to timeless literary figures such as Arthur and Merlin, and providing the basis of much European and world literature - the fantasy fiction genre, so popular today, was practically unknown before its publication.
It first came to general literary prominence in the mid 19th century, when Lady Charlotte Guest published her translation of 11 medieval Welsh folk tales under the title The Mabinogion.
The tales, which are outwardly concerned with the lives of various Welsh royal families - figures who represent the gods of an older, pre-Christian mythological order - are themselves much older in origin.
Preserved in written form in the White Book of Rhydderch (1300-1325) and the Red Book of Hergest (1375-1425), portions of the stories were written as early as the second half of the 11th century, and some stories are much older still.
It is from this older, oral tradition of story telling that many of the fantastic and supernatural elements of the tales have come.
Ironically the title, The Mabinogion, is a relatively modern one, coined mistakenly by Lady Charlotte Guest herself. The word 'mabinogion', which she assumed was the plural form of 'mabinogi', appears only once in the manuscripts she translated and is commonly dismissed as a transcription error.
'Mabinogi', derived from the word 'mab', originally meant 'boyhood' or 'youth' but gradually came to mean 'tale of a hero's boyhood' and eventually, simply, 'a tale'.
It's these first four heroic 'tales', or the four 'branches' of Pwyll, Branwen, Manawydan, and Math, which make up The Mabinogi(on) proper.
A single character, Pryderi links all four branches. In the first tale he's born and fostered, inherits a kingdom and marries. In the second he's scarcely mentioned, but in the third he's imprisoned by enchantment and then released. In the fourth he falls in battle.
The tales themselves are concerned with the themes of fall and redemption, loyalty, marriage, love, fidelity, the wronged wife, and incest.
They're set in a bizarre and magical landscape which corresponds geographically to the western coast of south and north Wales, and are full of white horses that appear magically, giants, beautiful, intelligent women and heroic men.
The title, The Mabinogion, is also used today to describe the other seven stories in Lady Charlotte Guest's collection: The Dream of Macsen Wledig, which is based on the legend of Emperor Maximus; Llud and Llefelys, a story full of fairy tale elements; Culhwch and Olwen, the earliest known Arthurian romance in Welsh; The Dream of Rhonabwy, a witty meditation on ancient Britain's heroic tradition; and three further Arthurian romances, The Lady of the Fountain, Peredur and Geraint and Enid. A 12th story, Taliesin, translated from a later manuscript, is included in some collections.