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.