Also known as "Leix", this region was part of the possessions of the O'Mores (or O'Moores) before the Norman invasion. As in so many cases, the Norman grant of the lands to the Fitzpatricks was largely unsuccessful and the native Irish remained a constant threat until the sixteenth century when, along with the neighbouring Offaly, Laois was annexed to the English crown under Queen Mary and renamed "Queen's county". In case the Irish still hadn't got the point, the principal town was also renamed Maryborough. The county was retitled Laois after Independence in 1922, and Maryborough became Portlaoise. The town is best known to most Irish people today as the home of the country's only high-security prison.
Physically, the county is centred on the valleys of the upper Nore and Barrow rivers; most of the Slieve Bloom mountains, with some of the most beautiful and secluded landscape in Ireland, are in Laois.
Surnames associated with the county include Fitzpatrick, Buggy, Bergin, Dunne, Deegan, Tynan, and Dowling.