This name, with variant spelling Coghlan, Co(u)ghlin and Cohalan, is an Anglicized form of two distinct Gaelic Irish sept names, the first being MacCochlain of County Offaly, and the latter, O Cochlain of County Cork. The Gaelic prefix "mac" indicates "son of" and "O", "male descendant of", plus the personal byname "cochlan" meaning "a short hooded cloak"; hence, "descendant of the cowled or hooded one". The MacCoughlan territory comprised the modern barony of Garry castle, County Offaly, and they had many strongholds in the Banagher - Clonmacnois area. Their chief was known as Chief of Delvin MacCoughlan. Records show that in 1665 two MacCoughlan families possessed over 3,400 acres of land in Co. Offaly. The (O) Coughlans of County Cork belonged to the baronies of Carbery and Ballymore where the name was most numerous at the time of Petty's "census" (1659), as it is to-day. The first recorded spelling of the family name is shown to be that of MacCoughlain of Co. Offaly, which was dated circa 1150, "The Annals of the Four Masters", during the reign of Dermot Mac Murrough, known as "The King of Ulster", 1134 - 1171. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.