Former Emperor Bao Dai made Saigon the capital of the State of Vietnam in 1949 with himself as head of state. After the Viet Minh gained control of North Vietnam in 1954, it became common to refer to the Saigon government as 'South Vietnam'. The government was renamed the Republic of Vietnam when B?o ??i was deposed by his Prime Minister Ngo Dinh Diem in a fraudulent referendum in 1955. Saigon and Cholon, an adjacent city with many Sino-Vietnamese residents, were combined into an administrative unit called ?? Th?nh S?i G?n (Capital City Saigon).