The Ngạn people are a small local population of Tai-language speakers in the eastern districts of Cao Bằng province in northernmost Vietnam. They are reportedly descendants of bodyguards hired by the Mạc royal court during the seventeenth century. It is the aim of this paper to investigate where they came from, using Vietnamese and Chinese ethnological studies, on-site fieldwork, and textual analysis. My preliminary conclusion is that the original homeland of the Ngạn was in the Youjiang River valley in central-western Guangxi. Numer-ous strands of information point to a strong connection with the native chieftaincy of Tianzhou, while the lyrics of traditional songs sung by the Ngạn point to the region of the former chieftaincy of Si’en, just to the east of Tianzhou.