Why did the Ming and Qing dynasties not cherish the national luck and insisted on preserving Korea?

Stavri Anoos, an American, said in his "Global History" that the tribute system used by China to adjust its relations with foreign countries applied the Confucian ethics on family to its relations with other countries. China, the dominant "China", is surrounded by inferior tributary countries, all of which are regarded as children. Just as children should obey and respect their parents, so should small countries treat China. Specifically, small countries regularly send tribute missions to pay tribute to Emperor China, including kowtowing, that is, kneeling three times and making nine obeisances. The number of such missions varies from country to country, depending on the proximity to China, such as several times a year in North Korea and once every 10 in Myanmar or Laos. Thus, the relationship between China and North Korea is the earliest and the closest. Therefore, the Ming Dynasty listed North Korea as an example of a vassal state. North Korea paid tribute to the Ming Dynasty to "do great things" and the Ming Dynasty adopted a policy of "whispering" to North Korea.

In fact, the monarchs and ministers of North Korea skillfully used this "trivial" ethical relationship to achieve the success of the aid plan when they asked for help from the Ming Dynasty. Despite the opposition of ministers, korean king and Li Yong resolutely abandoned Beijing and fled to Yongbyon Road, which borders the Ming Dynasty in the north. He declared several times that "it is ok to die in the country of the son of heaven, but not in the hands of thieves" and that "it is better to die in the country of parents than in the hands of thieves". His reason is nothing more than saying that North Korea's difficulties today are not its own problems, but caused by sticking to the "major events" festival and doing its best to be a subordinate. The implication is naturally that I hope that the Ming Dynasty will also fulfill the meaning of "Xiaoyan". In this way, North Korea tied the Ming Dynasty to its own chariot of interests from the ethical level of "helping the poor".