A collection of manuscripts, [12 cent.]-1909, from the library of Peniarth, Merionethshire, the core of the historic collection being that of the library accumulated at Hengwrt, Merionethshire, by Robert Vaughan during the seventeenth century. The collection includes many of the most important Welsh language manuscripts, including the Black Book of Carmarthen (Peniarth MS 1), the Book of Taliesin (Peniarth MS 2), the White Book of Rhydderch (Peniarth MSS 4-5) and Brut y Tywysogion (the Chronicle of the Princes) (Peniarth MS 20), as well as important manuscripts in other languages such as the Hengwrt Chaucer (Peniarth MS 392), the Law of Hywel Dda (Peniarth MS 28), Beunans Meriasek (Peniarth MS 105) and Bede's De natura rerum (Peniarth MS 540B).