Constituent Entity (also known as Sovereign Provinces, Constituent Kingdoms, or Constituent Nation) is used to refer to a sovereign entity that is within another sovereign nation. The Term originated in the United Kingdom but has expanded.
History of the Concept
New Union Treaty
In 1991, Mikhail Gorbachev Proposed the Union of Soviet Sovereign Republics as a way of keeping the Soviet Union together. This country, based on the provisions of the New Union Treaty, would have given each of the 15 Soviet Republics, complete autonomy with a central government controlling foreign policy, currency, inter-republic trade, and a military, as well as inter-republic territorial disputes. This did not go into effect due to the Collapse of the Soviet Union and the Soviet Government's attempt to overthrow Mikhail Gorbachev.
In 1995, to end the Conflict in Bosnia and Herzegovina, the Bosnians and the Serbian Nationalists (Republika Sprksa) signed the Dayton Accords. This allowed for the two countries to form their own governments while remaining a single country. Unlike the New Union Treaty, This Proposal did not give the entities autonomy, rather, keeping them separate as a federalist state.
Devolution of the British Government
During the Tony Blair Administration, the British "Countries" of Scotland, Wales, and Northern Ireland were each given their own Parliaments as part of an attempt to keep the union together. Over the years, each country has gained more and more autonomy and was forced to hold a referendum on Scottish Independence took place in 2014.
In 2016, the Scotland Act was passed by the United Kingdom. This law, gave Scotland more autonomy and allowed them to have full control over their borders. Similar Acts were passed in 2017 for Wales, England and Ulster (Northern Ireland)