Domnall Ó Brolcháin, a cousin of 'Flaithbertach Ua Brolcháin' both a builder and a clergyman, made notable contributions to the construction and governance of Iona Abbey. As a builder, he played a key role in reconstructing the cathedral, a central part of the abbey’s structure and religious life. In his role as a clergyman, he was involved in guiding the abbey’s affairs and spiritual community. His efforts highlight the value of craftsmanship and religious leadership during the medieval period.

There were known connections between the O Brolchains of Ireland and Iona. See the annal entries for 1164 and 1202. According to Reeves, this last entry describes an abbot of Iona, DONALDUS OBROLOHAN, whose inscription appears on the capital of the tower column, DONALDUS OBROLOHAN FECIT HOC OPUS [Donal O Brolchain made this work].

Black (Surnames of Scotland) appears to regard the family in Scotland as Irish in origin.

• The O Brolchain surname is on record in Scotland as early as 1549 in Islay, where Sir John Obrolchan held the rectory of Saint John the Evangelist.
• And in 1677 an Archilbald McBrolchin was a tenant in Iona.
• In 1778, a Lauchlan duy McBrolachan was a merchant in Campbeltown.
• It appears the Mac an t-Saoirs of Ireland were therefore kinsmen of the O Brolchains; and there were O Brolchains settled in the isles of Scotland from a very early date, probably dating from the era of the above Donaldus Obrolohan who inscribed his name on the church tower of Iona. Could the Irish Mac an t-Saoirs, perhaps in company with their O Brolchain kinsmen, have settled in Scotland as well?

The history of the MacIntyres of Scotland is about as misty as can be. All they seem to know for sure is that they sailed to their present homelands from an island to the west accompanied by a mysterious white cow and a prophecy about settling where the cow rested.

The white cow symbolism occurs frequently in Celtic mythology and is probably impossible to trace with certainty. But it is at least interesting to note that St. Bridgit of Ireland was associated with a white cow; that she built a nunnery at Kildare, and is most strongly associated with that area; and that the second O Brolchain Mac an t-Saoir referred to above, was Bishop of Kildare. In addition, each of the two O Brolchains were named Mael Bridghe, a name which signifies a "servant of St. Bridgit." Were both of these men, one of them probably the first Mac an t-Saoir of Ireland, members of a cult of St. Bridgit?

In short, I wonder if the Scottish Mac an t-Saoirs could have been Irish Mac an t-Saoirs, who sailed to their present homeland from Iona (or Ireland) around 1200 A.D. or a little later, perhaps settling first in Iona.

The O Brolchains were from the Barony of Clogher in Tyrone, but later removed to Derry, in the Inishowen Peninsula of County Donegal, adjacent to Derry County, probably because of their connections with the church of Columcille at Derry. There were many and varied connections between the Irish of this part of Ireland and the families of Scotland. Donal oge O'Donnell, the King of Tirconnell (Donegal) married first a MacSweeney and secondly a MacDonald; and he later imported MacSweeney gallowglasses from the isles of Scotland. Hugh MacDonald, in his history of the MacDonalds, mentions a marriage between Angus oge MacDonald and a daughter of O Cahane. As part of her retinue she brought with her to Scotland a number of men from the O Cahane territory in Derry and the Inishowen Peninsula (O Dohertys).

The Book of Clan Ranald has the following description of this retinue:

"Aonghus Og, son of Aonghus Mor, son of Domhnall, son of Ragnall, son of Somerled, the noble and renowned high chief of Innsigall. He married the daughter of Cuinnbhuighe O'Cathan. She was the mother of Eoin, son of Aonghus, and it is with her came the unusual retinue from Erinn, viz., four-and-twenty sons of clan families, from whom sprang four-and-twenty families in Alban."

Hugh MacDonald's text gives the names of some of these Irish families said to have settled in Scotland under the MacDonalds in the time of Angus oge:

"[Angus oge] married Margaret, daughter of Guy O'Kaine in Ireland. She was the mother of Brian Balloch O'Neill, of whom descended the O'Neals of both the Clan Buys. The portion or tocher he had by her was seven score men out of every surname under O'Kain, viz.: the Munroes, so called, because they came from the Innermost Roe-water in the county of Derry, their names being formerly O'Millans, the Roses of Killraack, the Fairns, Dingwalls, Glasses, Beatons, so now called, but improperly, that being a French name, whereas they are Irish, of the tribe of O'Neals, and took the name first from following the name of Beda. Our highland shenakies say that Balfour Blebo, and these Beatons that came from France, went formerly from Ireland, but for this they have no grounds to go upon. The Macphersons, who are not the same with the Macphersons of Badenoch, but are of the O'Docharties in Ireland; the Butikes in Butikes in Caithness, of whom is the Laird of Tolingail, and many other surnames, which, for brevity, we pass over, many of whom had no succession."

Going the other way, from Scotland to Ireland, we find the MacAlins, (i.e., Campbells from Clan Ailin), gallowglasses to the O Dochartaighs of Inishowen in Donegal, and probably the MacDebits (MacDavid) as well, although both of these families are spuriously claimed to be branches of the O Dochartaighs in a dubious passage in O'Clery's Book of Genealogies.

Most prominently we find the MacSweeneys holding massive territories in Donegal under the O'Donnell Kings; and the MacDonalds were well-known gallowglasses to the O'Neills in neighboring Tyrone.

Annals of Ulster 1164

Select members of the Commmunity of Ia (Iona in Scotland, namely, the arch-priest, Agustin and the lector (that is, Dubsidhe) and the Eremite, Mac Gilla-duib and the Head of the CeliDe, namely, Mac Forcellaigh and select members of the Community of Ia besides came on behalf of the successor of colum-cille, namely, Flaithbertach Ua Brolchain's acceptance of the abbacy of Ia, by advice of Somharlidh and of the Men of Airthir-Gaedhel and of Insi-Gall; but the successor of Patrick and the king of Ireland, that is, Ua Lochlainn and the nobles of Cenel-Eogain, prevented him.

Annals of Ulster 1202

Domnall Ua Brolchain prior [of Iona] , eminent senior select for intelligence, for form, for appearance, for disposition, for gentleness, for magnanimity, for benevolence, for piety, for wisdom, entered the way of all flesh, after great suffering and most excellent penance, on the 5th of the Kalends of May [Apr. 27].