Generic History of our Name The Cahill name is one of the oldest in Europe. The Irish had surnames very early, and O'Cahill was one of the first. The earliest recorded person of our name was a monk, Flan O'Cahill, who died in 938 A.D. It is extremely unlikely that anyone can trace a member of his or her family back to Flan's family. The O'Cahills have links back to Irish pagan leaders in the 200s and 400s A.D. By 1000 A.D. the O'Cahills controlled much of south Galway, east Clare, and western and northern Tipperary. This predominance was ended in the 1200s by the O'Shaugnessys and the O'Donoghues, perhaps both in alliance with the Norman-English who had recently arrived in Ireland. Those 13th century defeats may have led to the loss in most lines of their "O," which indicates both descent and predominance. However it happened, by 1659 the name "O'Cahill" had been almost entirely replaced by "Cahill" as a common surname in a listing of workers on the large farms following the English Cromwellian land confiscations. Today Cahill is the most common surname in Munster, the old southwestern province, which includes the counties of Clare, Limerick, Kerry, Cork, Waterford, and Tipperary. The Irish there pronounce it with the accent on the first syllable with a short "a" and in the last syllable an almost-swallowed "h". This can be described as pronounced "CA" (accented) as in cattle, and "hill" as hull