By 1976, Saudi Arabia had become the largest oil producer in the world. Khalid's reign saw economic and social development progress at an extremely rapid rate, transforming the infrastructure and educational system of the country; in foreign policy, close ties with the US were developed. In 1979, two events occurred which greatly concerned the government, and had a long-term influence on Saudi foreign and domestic policy. The first was the Iranian Islamic Revolution. It was feared that the country's Shi'ite minority in the Eastern Province (which is also the location of the oil fields) might rebel under the influence of their Iranian co-religionists. There were several anti-government uprisings in the region such as the 1979 Qatif Uprising.