Originally ruled as part of Bahrain, Qatar became an informal British protectorate in 1868. From 1872 until 1916, however, the sheikhs of Qatar were largely controlled by the Ottoman Empire and it was not until 1916 that Qatar was declared a formal British protectorate. The British withdrew from the area in 1971 and Qatar made some attempts to join the United Arab Emirates. This came to naught and the country decided on independence as of September 3, 1971. The healthy economy of Qatar rests on oil reserves, vast supplies of natural gas, the supply of shipping services, and banking.