Vietnam ruled from Qing Dynasty to Song Dynasty. Why hasn't it been assimilated?

From the perspective of world history, the Chinese nation has a long history, and other ancient civilizations were either slaughtered or absorbed and assimilated by other nations. In the 5,000-year history of China, only the Chinese nation has assimilated other nations, and no other nation can assimilate the Chinese nation.

Since the Qin and Han Dynasties, Annan region has been incorporated into Chinese territory, almost at the same time as Guangdong and Guangxi. After the Han, Jin, Wei, Jin, Southern and Northern Dynasties, until the Song Dynasty, 1200 years of history, Vietnam has been within the territory of China, ruled by China. This ruling time is long enough. Generally speaking, if a nation can be ruled for 300 years, it will basically be absorbed and assimilated. Why did Vietnam become a strong country in Southeast Asia instead of being assimilated 1000?

Actually, there are three main reasons. First, there are not enough immigrants in China. Many people can't understand why Guangdong and Guangxi can be assimilated, but Vietnam can't. The most important thing is that there are immigrants from China. In ancient Guangdong, places like Annan were wild places, and no one wanted to come. In order to stabilize this place, Qin Shihuang used 500 thousand troops to settle here, which also gave the ancient Han people an advantage in Guangdong. Up to now, 90% of Guangdong people are Han Chinese. In other words, Guangdong has gradually integrated into the Chinese nation, and the biggest contributor is Han immigrants, but Annan is different. Qin Jun did not enter Vietnam, and there were no large-scale immigrants after the Han Dynasty. Therefore, in Annan, Han people have always been very few, and there is no strong ability to reproduce and assimilate. This is the core point. If we had been able to station 200,000 troops, it is estimated that Vietnam would still belong to China.

Second, Han people were slaughtered in Vietnam. Before the Tang Dynasty, Vietnam was very stable. During the Three Kingdoms period, it was dark and this place was not lost. The most important reason is that I was educated in Vietnam. A group of Han people were sent to Vietnam as managers. Although the number of Han people is small, it is enough to stabilize the situation. In the middle and late Tang Dynasty, the Tang Dynasty waged a long-term tug-of-war in Annan. The Tang Dynasty recruited a large number of Han people to fight in Annan, which caused great losses to the local Han people. In the Five Dynasties and Ten Kingdoms period, the separatist melee also ruined the Han people. After the number of Han people in Annan decreased, the local ethnic groups took the opportunity to become bigger.

Another important point is the regional differences. Ancient Guangdong and Annan were desolate, but even more dismissive. Moreover, the northern part of Vietnam is mountainous and the road is very difficult to walk. China's ruling ability in this place has been very weak. Coupled with the fact that this place is far from the emperor, Vietnam is more likely to form a separatist regime and rebel forces. Ancient dynasties are also difficult to manage, and they are often too lazy to manage.

Because the dynasty doesn't care. So Annan went to war independently, which happened to be the Song Dynasty. The national strength of the Song Dynasty was so weak that it could not be restored. After several battles, there was no result. When I tried to take Annan back to the Ming Dynasty, I found it was too late.