Revenue stamps of the United Kingdom
When Ireland was partitioned into Northern Ireland and Southern Ireland in 1921, separate revenue stamps were issued for both entities. Southern Ireland stamps saw little use since that political entity was quickly superseded by the Provisional Government of Ireland and later the Irish Free State (both of which applied overprints on various British and Irish revenue stamps). However, Northern Ireland continued to use separate revenue stamps until the 1980s. Northern Irish revenues include Civil Service, Dog Licence, Excise and National Insurance stamps, among many others.
Provinces of Ireland
The earliest recorded mention of the major division of Ireland is in the Ulster Cycle of legends, such as the "Táin Bó Cúailnge". The "Táin" is set during the reign of "Conchobar Mac Nessa", king of Ulster, and is believed to have happened in the 1st century. In this period Ireland is said to have been divided into five independent over-kingdoms, or "cuigeadh" whose "rí" (kings) were of equal rank, not subject to a central monarchy. Pseudo-historians called this era "Aimser na Coicedach", which has been translated as: "Time of the Pentarchs"; "Time of the Five Fifths"; and "Time of the provincial kings". It was also described as "the Pentarchy".