When dealing with the issue of national land boundaries, whether a piece of land belongs to a country, and who the land recorded in the relevant history books "since ancient times" has always been one of the important criteria, especially in the East Asian countries of the Greater China Cultural Circle. In 1689, when the Qing Dynasty and the Russian Empire concluded the Treaty of Nebuchu, the most important argument of the Chinese side was that "the land has belonged to China since ancient times."
It is precisely because China attaches great importance to "since ancient times" that when China handles documents of cultural exchange, it is particularly cautious in the use of words and sentences, fearing that because of the emergence of inappropriate words and phrases, it will cause a situation of "rationalization" for future generations. The most direct embodiment of this rigor is the "Vietnamese change of name" incident in 1803.
In present-day Vietnam, since the Song Dynasty, its ruler was crowned the King of Annam, and the state of Annam was recognized as a "lie domain", and in the history books of The following Chinese dynasties, for most of the time, the word Annam was specifically referred to as Vietnam, but Annam always had its own self-proclaimed national name "Great Yue Kingdom".
In 1771, due to the vietnamese post-Lê Dynasty authorities disregarding the lives of the people and waging a large number of ordinary people into exile, Vietnamese society suffered a serious social situation. Eventually, the Thi Soc Uprising broke out, led by the three brothers Nguyen Van Đồng, Nguyễn Van Duc and Nguyễn Van Huy, who were farmers and small businesses
The rebel army soon engulfed the two real powers in the north and south of Vietnam at that time, the Trần Ại in the north and the Nguyễn nguyễn in the south, and in 1788 the Later Lê Dynasty was officially overthrown, establishing the nascent Thuc Son Dynasty. Since Vietnam at this time was a Vassal state of China and paid tribute endlessly, the Chinese Qing Emperor Qianlong believed that he had the obligation to "rise and perish", so he sent a large army to an army in November of the 1788 lunar calendar.
Since the Xishan Dynasty soon took the initiative to submit and recognized the "tribute obligation" of the Later Lê Dynasty, and King Nguyễn Van Hue personally went to Beijing in 1792 to celebrate the 80th birthday of the Qianlong Emperor, the Chinese Qing Dynasty did not further strengthen the army and vowed to restore the Lê Dynasty.
However, vietnam's internal contradictions did not calm down because of the establishment of the Tay Son Dynasty, and in 1802, after another civil war, the Sai Son Dynasty collapsed in the hands of Nguyen Phuc Anh, a descendant of the Nguyen family of the former Southern Lê Dynasty, and the Nguyễn Dynasty opened a new chapter in Vietnamese history.
Since Nguyen Phuc Anh himself was a powerful magnate of the Later Lê Dynasty and was familiar with the tributary rules of the Greater Chinese cultural circle, in order not to conflict with the Qing Dynasty of China, which had just established a "tribute" relationship with the Xishan Dynasty, he declared that the Nguyen Dynasty was the orthodox successor of the Later Lê Dynasty, and cleverly used the word "restoration" as a word to re-"pay tribute" to the Chinese Qing Dynasty.
However, the new Vietnamese monarch Nguyen Phuc Anh, who was raised by the Greater Chinese cultural circle and could write Chinese characters, played sloppy with the Chinese emperor in words. In 1803, he wrote to the Jiaqing Emperor, hoping that the Qing Dynasty of China would change the Vietnamese name Annam in its documents to "South Vietnam".
As a Vietnamese aristocrat well versed in Greater Chinese culture, he could not have been unaware that china had a historical South Vietnamese state that had ruled most of the southern parts of China south of the Yangtze River (the territory of the South Vietnamese state at its peak included guangdong, Guangxi (most of the region), Fujian (a small part of China), Hainan, Hong Kong, Macau, and Vietnam (most of the north and central regions).
The re-acquisition of the name "South Vietnam" in present-day Vietnam means that in the inheritance of the Greater Chinese cultural circle, present-day Vietnam will exist as the inheritance of the South Vietnamese state that once stood side by side with the Chinese Han Dynasty (the South Vietnamese state once ruled northern Vietnam).
Therefore, in the Greater China cultural circle, Vietnam's letter is a literal "claim" for the territory of southern China. It can be seen from this that Nguyen Phuc Anh is playing tricks on the Chinese emperor, and if the Jia Khanh Emperor at this time does not pay attention to agree, the "Great Vietnamese State" that Vietnam has been preaching internally will become a fact, and in legal terms, China's absolute sovereignty over the South will be loosened in the slightest.
If Vietnam had been strong that day, vietnam could have claimed "sovereignty" over southern China on the grounds of "the inheritance of the South Vietnamese state" and turned southern China into a "disputed land."
Fortunately, the Jia Khanh Emperor was not stupid, he saw through Nguyen Phuc Anh's routine, did not agree with "South Vietnam", but changed "Vietnam" to "South Vietnam".