Tonkin (Vietnamese:Bắc Kỳ, historically Đàng Ngoài), also spelled Tongkin, Tonquin or Tongking, 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. "Tonkin" is a corruption of Đông Kinh (東京), the name of Hanoi during the Lê Dynasty. Locally, Tonkin is known as Bắc Kỳ, meaning "Northern Region". Located on the fertile delta of the Red River, Tonkin is rich in rice production.