The chief location of the Ngai in Vietnam is in the island and coastal regions of Quang Ninh Province in the north. Others live in surrounding provinces. After 1954 some Ngai migrated to Saigon City in the southern part of the nation. Although their numbers are now tiny, the Ngai claim to have once been the original inhabitants of Quang Ninh. A document from the 10th century, the Annals of the History of the Viet Land, records that the Dan group had already existed in Quang Ninh for some time. The four other branches (Xin, Hac Ca, Khach Gia, Le) of the Ngai minority migrated to Vietnam at different stages over a long period of time. The Hac Ca are the most recent arrivals, having come from China in the early 1800s. Many Ngai have moved to Saigon since 1954.

 

      The Dan prefer to call themselves Soisangyan, a name which means 'waterborne people' in their dialect. In China, the Han Chinese insist "the Dan are not Han Chinese at all, but rather a distinct minority race."  Experts now generally agree that although the Dan are ethno-linguistically a Sinitic people (they speak a dialect of Cantonese), "there is no doubt that they have been discriminated against in the past, officially as well as socially…. It is clear they have developed a strong sense of group identity…. Such a castelike distinction is more typical of India than of China."  The Dan people are said to be Mongols who were forced by the Han to move from the hinterlands to the coast of Fujian during the decline of the Yuan Dynasty (1271-1368).
The strangeness of the Dan is reinforced by tales of  their short legs, useful only for life at sea. Not surprisingly, all customs of the Dan revolve around their lives on the water. Whole families live on small boats that "seldom if ever touch the shore. Children are born and raised on the boats, and dogs, chickens, and cats move freely from deck to deck. In the old days…little coffin boats carried each [Dan] person to his or her final resting place on land. For some, it was the first time on land as well as the last."   The Chinese have a saying that a Dan person "on the water is a veritable dragon, on land is only a miserable worm."