The territory in the Nagorno-Karabakh region belongs to Azerbaijan, but is de facto governed by the Republic of Artsakh, an internationally non-recognized state. The area was known as the Republic of Nagorno-Karabakh until 2017.
Nagorno-Karabakh was claimed by both the People’s Republic of Azerbaijan and the Democratic Republic of Armenia, when both countries became independent in 1918 after the fall of the Russian Empire and a brief war over Nagorno-Karabakh broke out in 1920. When the Soviet Union took control of Armenia and Azerbaijan, the Nagorno-Karabakh Autonomous Oblast (NKAO) was established in Azerbaijan SSR in 1923. During the fall of the Soviet Union, another conflict arose between the two countries, after Armenia organized a referendum in the NKAO, which led to a declaration of independence. As a result, a large-scale ethnic conflict arose that led to the Karabakh war between 1991 and 1994.