Don't underestimate the "salutation", in this simple title, it reflects the degree of "respect" of both parties for each other, and the degree of development of each other's relationship. Just like in some places now, the local colloquial "southern barbarians" and "northern servants" actually have a "contemptuous" color.

Modern China has also been extremely despised by neighboring "Little Japan", in their mouths, Chinese is nothing more than "Indochina". This kind of name is not "long-standing", as early as the Han and Tang Dynasties and the Two Song Dynasties, Chinese in the eyes of the Japanese, is the existence of "big brother", in 2010, Japan staged a TV series "Big Buddha Open Eyes", which reflected the Japanese at that time, "extreme worship of Chinese things." ”
But with the demise of the Southern Song Dynasty and kublai Khan's two failed declarations of war on Japan, they began to feel that China was not much better than it was. During the Ming Jiajing period, the Wokou frequently harassed the southeast coastal area, and even an offensive incident occurred, and dozens of Japanese entered from the coast of Jiangsu and fought all the way to Nanjing. During the Wanli Dynasty, Japan launched a frenzied attack on Korea, hoping to conquer China and India, but was defeated by the Joint Efforts of China and North Korea.
Thus, for the next 300 years, the coast of Northeast Asia was peaceful.
It can be said that for a period of time, "China" was a respect for the Chinese Han Chinese, and the word "Indochina" became popular in Japan after the Meiji Restoration. However, at that time, China's official national name was "Great Qing", so the Japanese government officially referred to China as "Qingguo" or "Great Qing Empire" and the Sino-Japanese War as "Japanese-Qing War". However, in the general folk press, China is generally referred to as "Indochina", the "Sino-Japanese War" as the "Japanese-Chinese War", and the Chinese language as "Indochina".
The Japanese did not call China's official national name "Daqing" but "China", and the Chinese Han chinese at that time, especially the Chinese revolutionaries, were not angry with Japan for calling China "China", but also had some gratitude. In 1868, the Meiji Restoration "transformed" a Japanese with rising strength, and after only 27 years, they easily defeated the Manchu Qing army. Since then, from top to bottom, Japan has no longer "looked down" on the "big brother" next door.
In 1913, the Japanese government, on the proposal of the Minister in China, agreed to change the title of "China" to "Republic of China" in the future.
This move aroused the anger of many Chinese.
China has had many beautiful names since ancient times: Huaxia, Shenzhou. In Japanese history, the title of China was often referred to as "Tang Tu", "Middle Earth", "China", etc., or by corresponding dynasties. So, why did the Japanese official change the "title" at this point in time?
On January 1, 1912, the Republic of China was founded, and after the Meiji Restoration, Japan no longer put "China" in the eyes, in order to continue to cultivate its own sense of national superiority, coupled with the consideration of the interests of all parties, so it unilaterally gave China a "national name". In 1930, the Nationalist Government in Nanjing sent a note to Japan that if, in the official documents of the Japanese side, the words "China" and other words continued to appear, the Chinese Ministry of Foreign Affairs had the right to refuse to accept it.
The Japanese government accepted this "protest," and from this year on, the word could not be found in official diplomatic documents. However, in ordinary diplomatic documents, the "custom is still followed". In 1931, Japan invaded and occupied northeast China and established a "puppet Manchu regime", in order to completely extinguish the local people's "Chinese nation" consciousness, slapped those who dared to call themselves "Chinese", were arrested, and forced them to call themselves "Manchukuo".
After Japan's defeat in the war, at the request of the Chinese delegation, the Allied Supreme Command, after investigation, confirmed that the title "Indochina" had the meaning of "contempt", and in 1946, the Allied Supreme Command ordered the Japanese Ministry of Foreign Affairs not to use the term "China" anymore. However, in the folk, this title continues to be used. Because, in the hearts of the Japanese people, "they lost to the United States, not China", all, did not really begin to respect Chinese.
On June 27, 1950, the U.S. military sent troops to Korea, and in November, the United States and South Korea joined forces to deploy troops on the Yalu River... After hearing this news from the radio by Japanese war criminals in Fushun, the attitude was very arrogant: "We are not war criminals, we are prisoners of war." The new Chinese government should send them back to Japan immediately. After that, fearing that they would continue to make trouble, the Chinese government moved the gang to Harbin to continue their transformation. On January 4, 1951, the news of the volunteer army's capture of Seoul reached Japan, and the whole country was shocked.
Six years ago, they lost to the United States, and now, the United States has been beaten by Chinese and "looking for teeth on the ground." Since then, the word "Indochina" has "disappeared" from Japanese folklore. The Attitude of the Japanese toward Chinese has changed to "equal treatment", and those Japanese war criminals no longer have any illusions. Junior officers began to "criticize" the leaders for their "war atrocities." Today, those Japanese born after the war can only learn by looking up the dictionary: "China" is the contemptuous name for "China" in the past.
From individuals to nations and countries, if they cannot prove themselves with "strength", in the end, in exchange for not only passive "beatings", but also verbal "insults". Although modern China, at the cost of 35 million Chinese sons and daughters, won the victory in the end, it was the victory that finally made the Japanese completely "dumb" was the victory of the War of Resistance Against the United States 6 years later, because it was the Chinese that defeated the "big god" in the hearts of the Japanese.
But can we guarantee that all this "will not recur"? Looking at history, it is clear that only by continuing to maintain strong national strength can we continue to truly gain the respect of others.
Therefore, speaking with strength is never a "vain statement".
Resources:
["History of the Second World War", "A Brief History of "China"】