Artsakh (/ˈɑːrtsɑːx, -sæx/ ART-sa(h)kh), officially the Republic of Artsakh or the Republic of Nagorno-Karabakh (/nəˌɡɔːrnoʊ kərəˈbɑːk/ nə-GOR-noh kər-ə-BAHK), was a breakaway state in the South Caucasus whose territory was internationally recognised as part of Azerbaijan. Between 1991 and 2023, Artsakh controlled parts of the former Nagorno-Karabakh Autonomous Oblast of the Azerbaijani Soviet Socialist Republic, including its capital Stepanakert. It had been an enclave within Azerbaijan from the 2020 Nagorno-Karabakh war until the 2023 Azerbaijani offensive, when the Azerbaijani military took control over the remaining territory controlled by Artsakh. Its only overland access route to Armenia after the 2020 war was via the five-kilometre-wide (3.1 mi) Lachin corridor, which was placed under the supervision of Russian peacekeeping forces.
The predominantly Armenian-populated region of Nagorno-Karabakh was claimed by both the Azerbaijan Democratic Republic and the First Republic of Armenia when both countries became independent in 1918 after the fall of the Russian Empire. A brief war over the region broke out in 1920. The dispute was largely shelved after the Soviet Union established control over the area, and created the Nagorno-Karabakh Autonomous Oblast (NKAO) within the Azerbaijan SSR in 1923; however, throughout the Soviet period, Armenians in the Nagorno-Karabakh Autonomous Oblast were heavily discriminated against. The Soviet Azerbaijani authorities worked to suppress Armenian culture and identity in Nagorno-Karabakh, pressured Armenians to leave the region and encouraged Azerbaijanis to settle within it, although Armenians remained the majority population.