Llyfr Gwyn Rhydderch

   Llyfr Gwyn Rhydderch (the White Book of Rhydderch) was written in the mid-fourteenth century for Rhydderch ab Ieuan Llywd of ParcRhydderch (the son of the Ieuan Llwyd who had possessed the Llawysgrif Hendregadreddin the 1330s). The manuscript contains evidence of at least five separate scribes or authors (evidence indicates that one of the scribes also copied the Llyfr Ancr Llandeibrefi). It contains Pedair Cainc y Mabinogi, Culhwch and Olwen, Lludd a Llefelys, the Dream of Macsen Wledig and many religious texts. A portion of the manuscript, known from copies to have contained the saga englynion, is now lost. The contents of the slightly later Llyfr Coch Hergest are closely related but that manuscript is not thought to be a direct copy.
   The manuscript became part of Robert Vaughan's library at Hengwrt in 1658 and remained there for two hundred years before it was obtained by WWE Wynne's library at Peniarth. It is now in the National Library of Wales (Peniarth MS 4 and 5), rebound into two volumes.