The Irish annals do not record the exact date of the 'perishing of the kine and swine of Ireland by a pestilence' within the century to which the Charter must be referred; but from the records in those Annals of the deaths of the persons mentioned in the Charter, it is certain that it must have been executed before A.D. 1140, in which year the death of Bishop O'Ceallaigh or O'Kelly is recorded by the Four Masters in the following words:
'A.D. 1140. Eochaid O'Kelly, head of the men of Meath, the most venerable bishop in all Ireland, died at an advanced age at Durrow Columbkille.'
See also Harris, in his edition of Ware's Bishops, says:
'Eochaid O'Kelly, Archbishop of the men of Meath, is mentioned in the anonymous Annals to have died in the year 1140.'126
The next named in this document of whom any notice is preserved in the Irish annals is Muredhach O'Clucain, Abbot of Kells, whose death is entered in the Annals of the Four Masters at the year 1154. The periods of some of the more distinguished lay chieftains
p.153mentioned can also be well ascertained, as that of Tiernan O'Rourke, 'King of the men of all Breifny.' This is the celebrated O'Rourke whose wife eloped with Dermot Mac Murrough, King of Leinster, in the year 1152, an event which is supposed to have been the original cause of the English invasion. This Tiernan makes his first appearance in Irish history in the year 1128, when he insulted and assaulted Celsus, Archbishop of Armagh, and killed some of his clergy, from which period forward he figures as one of the most conspicuous of the Irish chieftains till the year 1172, when he is slain on the hill of Tlachtgha, near Athboy, by Griffin, a nephew of Maurice Fitzgerald.
The next chief is Godfrey or Geoffrey O'Reilly. According to the Annals of the Four Masters he was banished into Connaught in the year 1154 by Murchertach O'Loughlin or Mac Loughlin, King of the north of Ireland, and was slain at Kells in the year 1161, by Melaghlin O'Rourke.
From these dates we may safely conclude that this document cannot be older than the year 1128, nor later than 1140, in which the venerable Bishop O'Kelly died.