Located in the southwestern Asia with Russia in the north and Iran in the south, Azerbaijan was divided between Russia and Persia (now Iran) in 1828. Following a short period of independence in 1918-1920, Azerbaijan was invaded by the Soviet Red Army in 1920 and had been a republic in the Soviet Union until it regained its independence after the collapse of the Soviet Union in 1991. Despite a 1994 cease-fire, Azerbaijan has yet to resolve its conflict with Armenia over the Azerbaijani Nagorno-Karabakh region (largely Armenian populated). Azerbaijan is rich in mineral resources, mainly oil and natural gas, and an oil production boom in recent years has led to remarkably high growth. However, the economy as a whole has not benefited as much as it might have done, and the promise of widespread wealth from development of Azerbaijan's energy sector remains largely unfulfilled.