His murder by Vikings at Clonmacnoise is recorded in the Annals of the Four Masters in 1106,[2] giving us a latest possible date and location for the main body of the manuscript.
Some time later, H (named for his addition of two homilies) added a number of new texts and passages, sometimes over erased portions of the original, sometimes on new leaves.
Based on orthography and an English loanword, Gearóid Mac Eoin concludes that H wrote in the late 12th or early 13th century.
[3] After the monastery of Clonmacnoise was broken up, the manuscript came into the possession of the O'Donnell dynasty of Donegal who held it until 1359, when it and the lost Leabhar Gearr were used to ransom members of the clan who had been taken prisoner by Cathal Óg Ó Conchobhair Sligigh (d. 3 November 1362).
Its location is unknown until 1837, when it was part of a collection owned by Messrs. Hodges & Smith of College Green, Dublin, and was cited by George Petrie in an essay on the History and Antiquities of Tara Hill.