The date of this Charter is fixed to the latter part of the eleventh century by our knowledge of the obits of three of the persons mentioned in it, namely, O'Clucain, Comharba of Kells; the Bishop O'Dunan; and Donnell, the son of Flann, King of Tara. According to the Annals of Ulster and the Four Masters, Ferdomhnach O'Clucain, Comharba of Kells, died in the year 1114. The death of Maelmuire O'Dunan, archbishop, is entered in the Annals of Ulster, the Annals of the Four Masters, and the interpolated copy of the Annals of Innisfallen, at the year 1117; but they differ as to the name of his see. The Four Masters call him Archbishop of Munster, and the Annals of Innisfallen Archbishop of Ireland. The old translation of the Annals of Ulster makes mention of two prelates of this name who died in 1117, namely 'Maolmure O'Dunan, chief Bishop of the Irish, and head of Ireland, clergy and laitye, for almes', &; and 'Maolmure O'Dunan, Archbishop of Munster.' In Mageoghegan's translation of the Annals of Clonmacnoise, at the year 1100, where an account is given of a synod held that year at Cashel, he is called 'O'Downan, arch Bushopp and Elder of Ireland.' In Harris's edition of Ware's Bishops, p. 467, 'Miler or Melmury O'Dunan, Archbishop of Cashel, is said to have died at Clonard, on the 24th of December, 1118, in the 77th year of his age.' And again, in the list of the Bishops of Meath, p. 140, 'Idunan, called Bishop of Meath, is said to have flourished in 1096.' The fact would appear to be that there was but one O'Dunan, and that he was Bishop of Meath, and that 'head of the clergy of Ireland for almes,' has been understood as meaning archbishop, when, in reality, it means nothing more
According to the Annals of Clonmacnoise, and the Four Masters, Domhnall or Donnell, the son of Flann, King of Tara, mentioned in this deed, was King of Meath, and was deposed and slain by his own people in the year 1094. It must, therefore, follow, that this document was drawn up sometime previous to that year.