Early History of Oriel
From the earliest of times the Airgilla or families of Oriel consisted of nine different family groupings, each occupying a well defined sub-region of the lands of Oriel. The Carroll of Oriel family are descended from one such family grouping, the Uí Chremthainn whose original lands would have been around Clogher in the modern Co. Tyrone.
The other family groupings were as follows:
Uí Mac Cairthinn, Uí Fiachrach, Uí Thuirtin, Fir Chraibe, Fir Lí, Airthur, Uí Meith and the Mugdorna.
However the families of Oriel were under pressure from two neighbouring kingdoms, the Cenel nEoghain to the west and the Uladh to the north. Over the centuries there was a process by which the Kingdom of Oriel repositioned itself further east into Co. Monaghan, to accommodate the expanding Cenel nEoghain. Inevitably there was conflict and in 637 and 638 A.D. a series of engagements around the present day town of Moira in Co. Down resulted in the Uladh been defeated by the Cenel nEoghain and the Airgilla. In 735 A.D. a battle was fought at Faughert in the modern Co. Louth in which the Uladh were again defeated. But in 827 A.D. at Leith Cam the Oriel families were defeated by the Cenel nEoghain.
Oriel had lost a lot of its influence by then and even its ancient site for the coronation of its Kings at Tulach Oc was in the hands of the Cenel nEoghain.
This remained the situation until King Donough O’Carroll started to expand and restructure the kingdom, winning back the lands lost over the previous centuries. The new Kingdom now consisted of a seaboard from just south of the River Boyne to the northern perimeter of the Mourne Mountains and west to Lough Erne. This remained the situation until the coming of the Normans.