The Synod of Rathbreasail in 1111, which first divided Ireland into territorial dioceses, included both Aghaboe and Kilkenny in the Diocese of Ossory, with the episcopal see at Kilkenny, whose abbey church became St Canice's Cathedral. The erroneous belief that the see was originally at Aghaboe and later transferred to Kilkenny is traced by John Bradley to a 16th-century misinterpretation of a 13th-century property transfer.
The Synod of Rathbreasail in 1111, which established territorial dioceses in Ireland, included both Aghaboe and Kilkenny within the Diocese of Ossory, with the episcopal seat at Kilkenny. The misconception that the see was initially located at Aghaboe before being moved to Kilkenny is attributed by John Bradley to a 16th-century misinterpretation of a 13th-century land transaction.