The Red River Delta or Hong River Delta is the flat low-lying plain formed by the Red River and its distributaries merging with the Thái Bình River in Northern Vietnam. Hồng is a Sino-Vietnamese word for "red" or "crimson". The delta has the smallest area but highest population and population density of all regions. The region, measuring some 15,000 square kil…The Red River Delta or Hong River Delta is the flat low-lying plain formed by the Red River and its distributaries merging with the Thái Bình River in Northern Vietnam. Hồng is a Sino-Vietnamese word for "red" or "crimson". The delta has the smallest area but highest population and population density of all regions. The region, measuring some 15,000 square kilometres 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.