Tonkin (Vietnamese: Bắc Kỳ, historically Đàng Ngoài), also spelled Tongkin, Tonquin or Tongking, is in the Red River Delta Region of northern Vietnam.
"Tonkin" is a corruption of Đông Kinh (東京), the name of Hanoi during the Lê Dynasty. Locally, Tonkin is known as Bắc Kỳ (北區), meaning "Northern Region".
The name was used in 1883 for the French colonial Tonkin protectorate, a constituent territory of French Indochina.
It is south of the Northeast Region of Vietnam, and of Yunnan and Guangxi Provinces of China; east of northern Laos; and west of the Gulf of Tonkin.
Located in the fertile delta area of the Red River, Tonkin is rich in rice production.
The area was called Văn Lang by Vietnamese ancestors from around 2000−100 BCE. Evidence of the earliest established society in northern Vietnam, along with the Đông Sơn culture, was discovered in the Cổ Loa Citadel area, the core of the ancient city of Cổ Loa. Its site is located near the historical city of Hà Nội and present-day Hanoi, the capital city of Vietnam.
According to Vietnamese myths the first Vietnamese peoples descended from the Dragon Lord Lạc Long Quân and the Immortal Fairy Âu Cơ. Lạc Long Quân and Âu Cơ had 100 sons before they decided to part ways. 50 of the children went with their mother to the mountains, and the other 50 went with their father to the sea. The eldest son became the first in a line of earliest Vietnamese kings, collectively known as the Hùng kings (Hùng Vương or the Hồng Bàng Dynasty). The Hùng kings called the country, which was then located on the Red River delta in present-day northern Vietnam, Văn Lang. The people of Văn Lang were referred to as the Lạc Việt.