Because when France colonized Vietnam, in order to better count the population, those Vietnamese without surnames changed to Ruan surnames. Because before that, ordinary Vietnamese could not have surnames, only princes and nobles could have surnames. When the French conducted a census in Vietnam in those years, for better statistics, they directly changed those Vietnamese without surnames to Nguyen surnames, so nearly half of the people in Vietnam today have the same surnames.

After Qin Shihuang unified the six countries, he sent general Zhao Tuo and hundreds of thousands of troops to conquer Guangdong, Guangxi and Vietnam. Since then, Viet Nam has become a province of China. However, the state of Qin soon perished. Zhao Tuo took the opportunity to establish South Vietnam. At that time, southern Vietnam included southern Guangdong, Guangxi and north-central Vietnam. At that time, the surnames of residents in South Vietnam were basically Qin Jun officials, so surnames were very complicated.

In 968 AD, Vietnamese Ding Buling wiped out 1 1 other countries and established the first feudal dynasty-Ding Dynasty. Ruan Dun, Ruan Shoujie and others helped Ding Buling unify Vietnam, and was named "Ding Guogong" and became a famous minister of the Ding Dynasty. Since then, in the Vietnamese dynasty, the Ruan family has flourished and become a big family in Vietnam. 1802, Ruan's descendants established the Ruan Dynasty with the support of France. Emperor Jiaqing named this country "Vietnam", which is the origin of Vietnam today.

In order to better colonize Vietnam, France implemented the household registration system in Vietnam. They found that almost half of the population in Vietnam had no surnames. In order to better manage them, France proposed that all Vietnamese without surnames should be Nguyen. Therefore, after the liberation of Vietnam, almost half of the population was Nguyen, and Nguyen became the first surname in Vietnam.