Miatsum (Armenian: Միացում, romanized: Unification) was a concept and a slogan used during the Karabakh movement in the late 1980s and early 1990s, which led to the First Nagorno-Karabakh War in 1992–1994.
The idea originated in an era of realignment among the Armenians who were unhappy that the area inhabited predominantly by an Armenian population has remained under the jurisdiction of Azerbaijan. From the 1970s, with the support of the first secretary of the Central Committee of Communist Party of Azerbaijan SSR, Heydar Aliyev, a policy of settling NKAO by Azerbaijanis was being implemented. The Armenian pogroms in Sumgait and Baku only exacerbated these trends, which led to military clashes between troops of the Republic of Azerbaijan and the forces of the Nagorno-Karabakh Defense Army (Artsakh).
Mountainous Karabakh should not be part of Azerbaijan not because Artsakh (the Armenian name for Karabakh) is an ancient Armenian land and Miatsum (unification) is a legitimate Armenian project, but because Azerbaijan allegedly mistreats its minorities.
The 1988 Karabakh movement started with the slogan "Miatsum" ("Unification" in Armenian).
Unity with Armenia, after all, had been the proclaimed goal previous to this (the slogan of the early phases of the Karabakh movement was miatsum, ‘unification’), and an annexationist policy endorsed by the Soviet Armenian parliament.