This name, with variant spelling Mongan, is an Anglicized form of the Old Gaelic O Mongain. The Gaelic prefix 'O' indicates 'male descendant of', plus the personal byname 'Mongan' referring to one with a luxurious growth of hair (from 'mong', long-haired, plus the diminutive suffix 'ain'). Three branches of this sept existed in ancient Ireland. The Ulster sept which gave its name to the parish of Termonomongan in County Tyrone is no longer numerous. The Munster Mangans, orginally belonging to Counties Cork and Tipperary, now have a wider distribution in County Limerick. The territory of the third sept lay in North Connacht where the name was phonetically Anglicized as Mongan. To-day, however the form Mangan is more prevalent in all areas. James Clarence Mangan (1803 - 1849), born in Shanagolden, County Limerick, was a poet of renown and contributer to the 'Nation' and 'United Irishman' journals. The first recorded spelling of the family name is shown to be that of Mangan, (the name borne by twelve families), which was dated 1665, 'The Hearth Money Rolls for County Tipperary', during the reign of King Charles 11 of England, 'The Merry Monarch', 1160 - 1185. 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.