The distinction between Huá and Yí (Chinese: 華夷之辨; pinyin: Huá Yí zhī biàn), also known as Sino–barbarian dichotomy, is an ancient Chinese concept that differentiated a culturally defined "China" (called Huá, Huaxia 華夏; Huáxià, or Xià 夏) from cultural or ethnic outsiders (Yí, conventionally "barbarians"). Although Yí is often translated as "barbarian", other translations of this term in English include "foreigners", "ordinary others" "wild tribes", and "uncivilised tribes". The Hua–Yi distinction asserted Chinese superiority, but implied that outsiders could become Hua by adopting Chinese values and customs.
Vietnamese dynasties competed for primacy, adopting the same descriptive term, "central state" (Trung Quốc 中國), while Chinese were "outsiders". For example, Emperor Gia Long used Trung Quốc as a name for Vietnam in 1805. Cambodia was regularly called Cao Man, the country of "upper barbarians".[Trung Quốc 中國), while Chinese were "outsiders". For example, Emperor Gia Long used Trung Quốc as a name for Vietnam in 1805. Cambodia was regularly called Cao Man, the country of "upper barbarians".
In the 1800s, Nguyễn rulers such as Emperor Minh Mạng claimed the legacy of Confucianism and China's Han dynasty for Vietnam. Vietnamese called themselves as Hán dân (漢民) and Hán nhân (漢人), while they referred to ethnic Chinese as Thanh nhân (清人) or Đường nhân (唐人). For example, Emperor Gia Long said Hán di hữu hạn (漢夷有限, "the Vietnamese and the barbarians must have clear borders") when differentiating between Khmer and Vietnamese.
As Vietnam conquered territory from the Khmer and Lao kingdoms and various tribes on the Central Highlands such as the Jarai and the Mạ, Emperor Minh Mạng implemented an acculturation integration policy directed at these peoples. He declared, "We must hope that their barbarian habits will be subconsciously dissipated, and that they will daily become more infected by Han [Sino-Vietnamese] customs."
Clothing was also affected by Nguyễn policies. Lord Nguyễn Vo Vuong ordered traditional wrapped-skirt and cross-collar clothing which is very popular in Sinosphere to be replaced by Qing and Ming-style clothing  although isolated hamlets in northern Vietnam continued to wear skirts until the 1920s. The ao dai was created when tucks, which were close fitting and compact, were added to this Chinese style in the 1920s.
The White Hmong have also adopted trousers, replacing the traditional skirts that females wore.
Up to 1812, the 1644 Ming Datong calendar was used by the Nguyen in Vietnam.