Domhnall Ua Dubhthaigh, who died at Clonmacnoise in 1136, is recorded in the Irish annals as "Archbishop of Connacht, and successor of Ciaran, head of the wisdom and hospitality of the province".
In 1134 Ua Dubhthaigh acted as ambassador of King Tairrdelbach Ua Conchobair to Cormac Mac Carthaigh, King of Munster, who had "again assembled the Munstermen, Leinstermen, Conmhaicne, the men of Midhe, the Galls of Dublin, Waterford, Wexford and Cork, and the Uí Eachach and Corca Laoighdhe on sea, to proceed into Connacht."
This Treaty of Abhall Ceithearnaigh brought an end to a bitter war for supremacy between Connacht and Munster that had been on-going since the 1120s, and had the previous year resulted in the destruction of the castle and fleet of Dun Gallimhe, and Mac Carthaigh's defeat of Conchobhar Ua Flaithbheartaigh at the battle of An Cloidhe.
In 1143, the same crisis played out again: His own son, i.e. Ruaidhri, was taken by Toirdhealbhach Ua Conchobhair, in violation of laity and clergy, relics and protection.
The issue was resolved, if not ended, when in 1144 "Ruaidhri Ua Conchobhair, son of Toirdhealbhach, was released from fetters by his father, at the intercession of the clergy."
These were they: the altar of Ciarán, with its relics; the shrine of Ciarán, called the Oreineach; the Matha-mor; the abbot and the prior, and two out of every order in the Church; Muireadhach Ua Dubhthaigh, the archbishop, the lord of Connacht; the successor of Patrick, and the Staff of Jesus; the successor of Feichin, and the bell of Feichin; and the Boban of Caeimhghin.
A successor in the Archbishopric, Cadhla Ua Dubthaigh, was second Archbishop of Tuam and ambassador to Henry II (r. 1154–1189) in 1175.