Preiddeu Annwfn or Preiddeu Annwn (English: The Spoils of Annwfn) is a cryptic poem of sixty lines in Middle Welsh, found in the Book of Taliesin. The text recounts an expedition with King Arthur to Annwfn or Annwn, the Welsh name for the Celtic Otherworld.
Preiddeu Annwfn is one of the best known of mediaeval British poems. English translations, in whole or in part, have been published by R. Williams (in William Forbes Skene's Four Ancient Books of Wales), by Robert Graves in The White Goddess and by Roger Sherman Loomis, Herbert Pilch, John T. Koch, Marged Haycock, Sarah Higley. At some points it requires individual interpretation on the part of its translators owing to its terse style, the ambiguities of its vocabulary, its survival in a single copy of doubtful reliability, the lack of exact analogues of the tale it tells and the host of real or fancied resonances with other poems and tales.
A number of scholars have pointed out analogues in other medieval Welsh literature: some suggest that it represents a tradition that evolved into the grail of Arthurian literature. Haycock (in The Figure of Taliesin) was the first to point out that the poem is "about Taliesin and his vaunting of knowledge", and Higley calls the poem "a metaphor of its own making—a poem about the material 'spoils' of poetic composition".
The poem is uniquely preserved in the Book of Taliesin (Aberystwyth, NLW, MS Peniarth 2), which has been dated to the first quarter of the 14th century. The text of the poem itself has proved immensely difficult to date. Estimates range from the time of the bard Taliesin in the late 6th century to the completion of the manuscript. On the basis of linguistic criteria Norris J. Lacy suggests that the poem took its present form around AD 900. Marged Haycock notes that the poem shares a formal peculiarity with a number of pre-Gogynfeirdd poems found in the Book of Taliesin, that is, the caesura usually divides the lines into a longer and shorter section. She contends, however, that there is no firm linguistic evidence that the poem predates the time of the Gogynfeirdd.