The Sán Dìu (also known as San Deo, Trai, Trai Dat and Man Quan Coc; Chinese: 山由族; pinyin: Shān yóu zú; Jyutping: saan1 jau4 zuk6; Cantonese Yale: Sanyau Juk; Chữ nôm: 𠊛山由; Vietnamese alphabet: Người Sán Dìu) are a Yao ethnic group in northern Vietnam who speak Yue Chinese (Cantonese), a Sinitic language. They are believed to have migrated from Guangdong, China around 1600^{[citation needed]}.

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The group's estimated population as of 2000 was 117,500; the 2019 census put the number at 183,004.^[1] They speak a variant of Cantonese, and it is suggested that some still speak Iu Mien.^{[citation needed]} The major religions are Mahayana Buddhism and Taoism, with elements of animism and veneration of the dead. About 400 are adherents of the Catholic Church; a few are evangelical Protestants. This ethnic group is mainly concentrated around the Tam Đảo range in Thái Nguyên Province.

• List of ethnic groups in Vietnam
• Hoa people
• Ngái people