Tohill is of Irish origin and derives from O'Tuathail translating as "The descendants of the mighty people." Who these "mighty people" were is not proven, but as Ulster was the first province to be occupied by the Vikings in the 7th century a.d. it is possibly a reference to them. In anglicised form the more usual spelling is Toghill although Tohill has become the more accepted spelling over the past two centuries. The original home of the clan was the parish of Desertoghill. In the South the spelling form is usually Toohill and Twohill, although research suggests that these maybe a form of O'Toole. There are several variant forms of the name and examples are given below. Early research is hampered by the fact that many unreplaceable records were lost in the burning off the Public Records Office in Dublin by Sinn Fein in the 1922 Civil War. The examples include Mary Tohill of Bellaghy, Londonderry, on August 26th 1864, John Tohill of Mullingar, Westmeath, on April 4 1865, and Thomas Touhill of Galway, on April 14th 1866. The first recorded spelling of the family name is shown to be that of Michael Tohill, which was dated 26th May 1834 in the church register of Asheaton, Limerick, during the reign of King William 1V of England 1830 - 1837. 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.