Revenue stamps of Northern Ireland
Upon the partition of Ireland in 1921, separate revenue stamps began to be issued for both Northern Ireland and Southern Ireland. The latter were withdrawn soon afterwards upon the establishment of the Provisional Government, but the former continued to issue revenue stamps until the late 20th century. The need for separate issues for Northern Ireland came about since taxes raised there were meant to remain in the country. Most Northern Irish revenue stamps were British key types with appropriate inscriptions, but there were a number of different issues as well.
Counties of Northern Ireland
The English administration in Ireland in the years following the Anglo-Norman invasion of Ireland created counties as the major subdivisions of an Irish province. This process lasted a period from the 13th to 17th centuries, however the number and shape of the counties that would form the future Northern Ireland would not be defined until the Flight of the Earls allowed the shiring of Ulster from 1604.