Red River Delta

The Red River Delta or Hong River Delta (Vietnamese: Đồng bằng sông Hồng) is the flat low-lying plain formed by the Red River and its distributaries merging with the Thái Bình River in Northern Vietnam. Hồng (紅) is a Sino-Vietnamese word for "red" or "crimson". The delta has the smallest area but highest population and population density of all regions in Vietnam. The region, measuring some 15,000 square kilometres (6,000 sq mi) is well protected by a network of dikes. It is an agriculturally rich and densely populated area. Most of the land is devoted to rice cultivation. After the 2025 merger of Vietnamese provinces and cities, the Red River Delta includes four provinces and two municipalities. Its population totaled to nearly 23 million in 2019. Two of the four provinces, Bắc Ninh and Quảng Ninh, became municipalities in September 2026. In 2021, Paul Sidwell proposed that the locus of Proto-Austroasiatic languages was in this area about 4,000–4,500 years before present. The Hong River Delta is the cradle of the Vietnamese nation. Water puppetry originated in the rice paddies here. The region was bombed by United States warplanes during the Vietnam War. The region was designated as the Red River Delta Biosphere Reserve as part of UNESCO's Man and the Biosphere Programme in 2004.