Bahrain has been headed since 1783 by the Al-Khalifa family, who expelled the Persians as rulers of the nation. Previously, Bahrain had been a British protectorate from 1861 until independence in 1971. The country is now a constitutional monarchy with an elected legislative assembly. Endowed with smaller oil resources than its neighbors, Bahrain has turned to petroleum processing and refining and has transformed itself into an international banking center. Its economy has become one of the most advanced and diversified in the region.