Historically, most of present-day Kuwait was part of ancient Mesopotamia. Before the discovery of oil, Kuwait was a strategic trade port between Mesopotamia, Persia and India. Oil reserves were discovered in commercial quantities in 1938. In 1946, crude oil was exported for the first time. From 1946 to 1982, the country underwent large-scale modernization, largely based on income from oil production. In the 1980s, Kuwait experienced a period of geopolitical instability and an economic crisis following the stock market crash. In 1990, after oil production disputes with neighbouring Iraq, Kuwait was invaded, and later annexed into one of Iraq's governorates by Iraq under Saddam Hussein. The Iraqi occupation of Kuwait came to an end on February 26, 1991, after military intervention by a military coalition led by the United States and various other countries.