Original: On December 10 1991, as the Soviet Union was collapsing, a referendum held in the NKAO and the neighboring Shahumian region resulted in a declaration of independence from Azerbaijan as the Nagorno-Karabakh Republic.
Simplified: On December 10 1991, a referendum held in the NKAO and the neighboring Shahumian region resulted in a declaration of independence from Azerbaijan as the Nagorno-Karabakh Republic.