It is referenced in a translation of the historical Annals of the Four Masters by John O'Donovan that Domhnall Caomhánach was fostered for his training and education at the monastery of Saint Cóemgen/Kevin at Kilcavan in the Barony of Gorey, County Wexford.

[3] According to Irish custom, it was because of this that Domhnall assumed the name Caomhánach in the form of a descriptive byname meaning "a student or follower of Cóemgen".

The territory of the Caomhánachs at this period was huge and became known as "the Kavanagh's country" and with good reason: Art held complete control over it, reigning for forty-two years, and even receiving dues from the English crown, the "black rent" as it was known.

The last king of Leinster was Domhnall Spainneach Mac Murrough Caomhanach, who finally submitted at the end of the Nine Years' War in 1603.

Despite the family's loss of power and property, the line of descent from the last duly inaugurated Chief of the Name, Brian Kavanagh, The Mac Murchadha, remained unbroken down to recent times.

It is not surprising, then, that Caomhánachs were prominent among the great wave of native Irish aristocrats emigrating to Europe in the wake of the final defeat of Gaelic Ireland at the end of the seventeenth century, becoming officers in the armies of Catholic France, Spain and Austria.

[12] Clann Chaomhánach covers the following known variations of the family name—Kavanagh, Cavanough, Kavanaugh, Kavanah, Kavenah, Kabana, Kavaner, Kavenaugh, Kavenagh, Kavanacht, Kaveny, Cavanagh, Cavanaugh, Cavanah, Cavenah, Cavenagh, Cavany, Cavani, Kavana, Cavana, Cavner, Cavenaugh, Cavender, Cavenogh, Cavnar, Cavignac, Cavaignac, Cavanaogh, Cavanogh, Cabanah, Chaomhanach—but there are many others.