How can states cease to exist through merger?

States can cease to exist through a merger when two or more previously sovereign political entities unite to form a single, new state. In this process, the original states lose their separate international legal personalities and are replaced by a unified entity that assumes the rights and obligations of the predecessors.

A prominent historical example of this process is the unification of North and South Yemen in 1990, where both entities merged to create a single sovereign state.1

It is important to distinguish merger from other forms of state extinction:
* Absorption: One state incorporates the territory and population of another, which then ceases to exist (e.g., the accession of the Länder of East Germany into the Federal Republic of Germany in 1990).1
* Dissolution: An existing state breaks apart, resulting in the creation of multiple new, separate states (e.g., the division of Czechoslovakia into the Czech and Slovak republics in 1993).1
* Dismemberment: A larger state ceases to exist while its territory is divided among new states, sometimes with one successor state continuing the original's identity (e.g., the collapse of the Soviet Union in 1991).1