Armenians and Azerbaijanis lived side by side when both countries were part of the Soviet Union, but century-old ethnic enmity reignited when communism collapsed. Nagorno-Karabakh, mainly ethnic Armenian, ended up as part of Azerbaijan. Armenia won a war over the territory in the early 1990s that killed some 20,000 people and displaced a million, mostly Azerbaijanis.

Azerbaijanis were expelled not only from Nagorno-Karabakh itself but also from seven surrounding districts, including Kelbajar, that had been mostly inhabited by Azerbaijanis. The entire region became the internationally unrecognized, ethnic Armenian Nagorno-Karabakh Republic. Azerbaijan’s desire to return its citizens who had been displaced from their homes became a driving force in its politics.