Tonkin is the northernmost part of Vietnam, south of China's Yunnan and Guangxi Provinces, east of northern Laos, and west of the Gulf of Tonkin. Locally, it is known as Bac Ky, meaning 'Northern Region'. Located on the fertile delta of the Red River, Tonkin is rich in rice production. Its capital was Ha Noi, or Hanoi, which is now capital of unified Vietnam After the Viet Minh army defeated the French at the Battle of Dien Bien Phu (in Western Tonkin) in 1954, the republic transformed into what became known as North Vietnam, consisting of Tonkin and North-central Vietnam.