The best introduction to Welsh manuscript pedigree books is the comprehensive survey by Major Francis Jones entitled 'An Approach to Welsh Genealogy' in Transactions of the Honourable Society of Cymmrodorion, (1948), 303-466.
The manuscript pedigrees in the Library vary from descents of nobility, compiled in the later Middle Ages and copied time and again with additions by later genealogists, to charts which are the work of amateurs of modern times who have given copies of their compilations to the Library.
Many of the pedigree books do not continue after the end of the 17th century, while the lack of a fixed surname and the absence of place-names in the parish registers often mean that modern researchers can with certainty go no further back than the mid-18th century in their quest.
It often happens, therefore, that any sources giving information concerning the period around 1700 are of crucial importance. Handwritten pedigrees of hundreds of families are described in the Handlist of Manuscripts in the National Library of Wales. They include copies of such well-known compilations as the Taicroesion manuscripts by John Ellis (b. 1684: e.g. NLW MSS 1517, 1519), which relate mainly to Gwynedd, and the manuscripts of Alcwyn C Evans (1828-1902: NLW MSS 12356-7, 12359-61), which relate mainly to south-west Wales.
The largest group of early pedigree books is in the Peniarth Collection described in the Report on Manuscripts in the Welsh Language, I, Parts 2-3 (London: HMSO, 18991905). Others of importance are among the Wynnstay Manuscripts and Documents, and in the Castell Gorfod Collection.
The Wynnstay pedigree books consist mainly of transcripts, by Joseph Morris (d. 1860) of Shrewsbury, of many important manuscripts, including transcripts (Wynnstay MSS 1434) of the pedigrees compiled in the 17th century by Owen Salusbury of Rug and John Salusbury of Erbistock which were lost in the fire at Wynnstay in 1858. These are of particular value for north-east Wales. Among the pedigree books in the Castell Gorfod Collection is a copy (MSS 7 (i-xxi) and 12) of the Golden Grove Book of Pedigrees, which is now deposited at the Carmarthenshire Record Office.
For searchers particularly interested in the pedigrees of gentry families there are several important printed works available:
To see the pedigree books you should go to the South Reading Room.
To see the printed works you should go to the North Reading Room.