Liber Landavensis

The Book of Llandaff (Latin: Liber Landavensis; Welsh: Llyfr Llandaf, Llyfr Llan Dâv, or Llyfr Teilo), is the Chartulary, or Register Book of the Cathedral Church of Llandaff, a 12th-century compilation of documents relating to the history of the diocese of Llandaff in Wales. It is written primarily in Latin but also contains a significant amount of Old and Middle Welsh names and marginalia.

The work was compiled around 1125 by an unknown official at Llandaff Cathedral. It contains numerous records covering five hundred years of the diocese's history, including the biographies or Lives of Saints Dubricius, Teilo and Oudoceus and, most importantly for historical research, 149 land-grant charters. These Llandaff Charters give details of property transfers to the cathedral from various local kings and other notaries, from the late 6th to the late 11th century. (About 40% belong to the 8th century and 20% to the late 9th century.) The manuscript includes the document Fraint Teilo, in the original Middle Welsh with facing Latin version, an important source for the study of early Middle Welsh; although transcribed in the beginning of the twelfth century, the orthography suggests a considerably earlier provenance.

The book was compiled from a pre-existing collection of nine charter groups, originally entered in Gospel Books, and appears to have been produced to help in Bishop Urban's diocesan boundary disputes with the dioceses of St David's and Hereford. Many of the supposed early charters have therefore been 'edited' to serve Llandaff's interests. They are also undated and many are corrupt. However, through her exhaustive study of these documents, Professor Wendy Davies has reconstructed much of the original text and calculated probable time-frames. This work has been accepted by most historians, but criticized in some non-academic quarters.

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