The Popol Vuh survives because a Dominican priest, Francisco Ximenez, copied an alphabetic Kiche text at Chichicastenango in the early eighteenth century and set a Spanish translation beside it. That manuscript is now Ayer MS 1515 at the Newberry Library in Chicago. The Kiche original he copied is lost, and the text he copied was itself written down between about 1554 and 1558 from something older, so the book stands at two removes from anything ever performed aloud.
Classic Maya art shows that the tradition is much older than any of that. Codex style vases of the seventh and eighth centuries carry paired young lords whose name glyphs are read as Hunahpu and Xbalanque, shown shooting a great bird out of a tree, attending the resurrection of the Maize God from a cracked turtle shell, and in scenes of decapitation and of the ballgame. The correspondences are close enough for the identification to be accepted, while the differences are real: the Classic material gives the Maize God a far larger part than the Popol Vuh does, and the fit between the two is a working reconstruction rather than a match.
That gap is the interesting part. A colonial period book in the Latin alphabet turns out to preserve, imperfectly, a narrative that painters knew eight hundred years earlier. The pottery is now read partly through the book, and the book is corrected by the pottery, which is an unusually direct case of two kinds of evidence holding each other up.