Jiuzhen (Vietnamese: Cửu Chân, Chinese: 九真) was a Chinese commandery within Jiaozhou. It is located in present-day Thanh Hóa Province, Vietnam.
Michel Ferlus (2012) and Frédéric Pain (2020) propose that 九真 Old Chinese *kuˀ-cin transcribed *k.cin, a local autonym which is reflected in Puoc ksiːŋ muːl & Thavung ktiːŋ² meaning "human being, people". Both ksiːŋ and ktiːŋ² are from Proto-Vietic *kciːŋ, which consists of prefix *k- and root *ciɲ (“leg, foot”); thus, "human beings" are "(those who are) on foot", "those who stand on their feet."
Pain further suggests that " might therefore have been inhabited by some ancestors of the Southern Vietic Thavung - Aheu."
History
In 111 BC, Jiuzhen was formed after the Han conquest of Nanyue.
In 157, Chu Đạt rebeled in Jiuzhen and was defeated.
In 377, Li Xun seized Jiuzhen.