Corpus of Electronic Texts Edition
The Irish Charters in the Book of Kells (Author: [unknown])

section 21

No. 6—Page 142

The date of this document can be fixed to about the middle of the twelfth century by the notices of the more illustrious persons therein mentioned, namely, Muirchertach O'Loughlin; Dermot O'Melaghlin; Gilla-mac-Liag, Comharba of St. Patrick; and Edru O'Miadhachain, Bishop of Meath.

¶1] Muirchertach O'Loughlin was monarch of Ireland 'without opposition,' in the year 1161, about which time he granted a Charter to the monastery of Newry. He was slain in the year 1166.

¶2] Dermot O'Melaghlin was contemporary with the monarch Muirchertach O'Loughlin, and survived him several years. He was appointed King of Meath in the year 1157 by the Synod of Mellifont, in the place of his brother Donnchadh, who was excommunicated by the same Synod.

¶3] Gilla-mac-Liag, or Gelasius, Comharba of Patrick, was Archbishop of Armagh. He succeeded in the year 1137, and died in 1174.

¶4] Edru O'Miadhachain, Bishop of Meath, succeeded in 1150, and died in 1173 or 1174. He assisted at the Synod of Kells in 1152.

From these historical notices it is evident that this document cannot be older than the year 1157, when Dermot O'Melaghlin became King of Meath, nor more modern than 1174, when Archbishop Gilla-mac-Liag, or Gelasius, died.