Leinster is a province of Eire, occupying the eastern coastal and central portions, bounded on the north by Ulster Province (Northern Ireland), on the east by the Irish Sea and St George's Channel, on the south by the Atlantic Ocean, and on the west by Connaught Province and Munster Province provinces. It has an area of 7619 square miles. The province is subdivided into 12 counties, five of which lie along the Irish Sea.
The southern part of Leinster once formed the ancient Gaelic province of Leinster, or Laighan, and was ruled by the McMurroughs, kings of Leinster until the last half of the 12th century. In 1170, Richard Strongbow married the daughter of the last king, Diarmid, and received Leinster as a fief from Henry II of England. The northern part of the province once formed the ancient Kingdom of Meath.