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."^[1][2]

Pain further suggests that "Cửu Chân might therefore have been inhabited by some ancestors of the Southern Vietic Thavung - Aheu."^[2]

In 111 BC, Jiuzhen was formed after the Han conquest of Nanyue.^[3]

In 157, Chu Đạt rebelled in Jiuzhen and was defeated.^[4]

In 377, Li Xun seized Jiuzhen.^[5]

• Ferlus, Michel (2012). "Origine des noms anciens du Cambodge: Fou-nan et Tchen-la. L'interprétation des transcriptions chinoises". Péninsule. 65 (2): 47–64.
• Pain, Frederic (2020). ""Giao Chỉ" ("Jiāozhǐ") as a diffusion center of Chinese diachronic changes: syllabic weight contrast and phonologisation of its phonetic correlates". Tsing Hua Journal of Chinese Studies. 40 (3): 1–57.
• Twitchett, Denis (2008), The Cambridge History of China 1, Cambridge University Press
• Taylor, Jay (1983), The Birth of the Vietnamese, University of California Press
• Taylor, K.W. (2013), A History of the Vietnamese, Cambridge University Press