Rhygyfarch ap Sulien (1056/7–1099) belonged to the family that controlled the clas of Llanbadarn in the eleventh century. His father Sulien was bishop of St Davids, and Rhygyfarch's Life of St David has always been in some sense a well-known work. He identifies himself as the author in the concluding chapter, where he modestly asks his attentive readers to pray ‘for me, who am named Rhygyfarch and who rashly applied my inadequate talent to this subject’. This sentence is included in two versions of the text, however, and at different periods now one, now the other has been accorded precedence as representing most nearly the original work of the author.

From the twelfth century the shorter version was quite widely available in manuscript; an abridged copy was first printed in 1516, and other printed editions of all or part of the work appeared in 1645, 1668, and 1691. The latest of these editions, in Anglia Sacra, edited by Henry Wharton (1664–1695), was the first to draw on the longer text preserved uniquely in a manuscript from Brecon priory which by the seventeenth century was bound with other items in the library assembled by the famous book-collector Sir Robert Cotton (1571–1631), where it was shelved under the bust of the Roman Emperor Vespasian with the shelf-mark Vespasian A. xiv manuscripts, Vitellius E. vii, which was a copy of the Life as revised by Gerald of Wales towards the end of the twelfth century.