Northern Ireland, sometimes referred to as "Ulster Province," since it largely consists of that ancient province, has six counties: County Londonderry, Armagh, County Antrim, Down, County Fermanagh, and Tyrone. The majority of its population is Protestant, and favors the continued political union with the United Kingdom. Catholics, although a majority in Ireland as a whole, are a minority in Northern Ireland. This had led to prolonged conflict.
Between 1800 and 1920, all of Ireland was officially included in the United Kingdom. The Irish struggle for independence led to the Irish Free State (now the Republic of Ireland) in 1921. The counties that refused to join it at that time became Northern Ireland.