The Troubles
The Government of Ireland Act 1920 partitioned the island of Ireland into two separate jurisdictions, Southern Ireland and Northern Ireland, both devolved regions of the United Kingdom. This partition of Ireland was confirmed when the Parliament of Northern Ireland exercised its right in December 1922 under the Anglo-Irish Treaty of 1921 to ""opt out"" of the newly established Irish Free State. A part of the treaty signed in 1922 mandated that a boundary commission would sit to decide where the frontier of the northern state would be in relation to its southern neighbour. After the Irish Civil War of 1922–1923, this part of the treaty was given less priority by the new Dublin government led by W. T. Cosgrave, and was quietly dropped. As counties Fermanagh and Tyrone and border areas of Londonderry, Armagh, and Down were mainly nationalist, the Irish Boundary Commission could reduce Northern Ireland to four counties or less.
Administrative geography of the United Kingdom
Northern Ireland was the first part of the British Isles to have a devolved government, under the Government of Ireland Act 1920, and that continued until the Parliament of Northern Ireland was suspended in 1972. After a period of direct rule by the Westminster government and some abortive attempts at reinstating devolved government during the Troubles, the present-day Northern Ireland Assembly was established in 1998, and is currently in operation following a number of periods of suspension. The complex history of Northern Ireland has led to differing views as to its status. The term "Province" is often used by unionist and British commentators to refer to Northern Ireland, but not by nationalists.