Why hasn't China broken the opposing concept of "Yi Xia" in its history?

For China people, Emperor China obeyed the fate of the Netherlands, while China was a "central country" and was "enlightened by Confucius and Mencius' rites and music, surrounded by" barbarians who didn't know the etiquette ". But from the historical reality, the opposition of "Yi Xia" as a cultural concept is both absolute and relative. It is absolutely because the dominant position of Chinese culture can never be changed, because the Central Plains culture has always been in a dominant position in history, which can never be changed by any force. Although Mencius' personal prejudice is "I've heard that it changes in summer, but I've never heard of it", it's also unfortunate. The "one summer" model has different performances in different times. A strong sense of subjectivity has made China culture adapt to the challenges of different cultures and times in its development, and has always maintained uninterrupted continuity and stability. The process of "four changes" integration led by China culture has been going on. Relatively speaking, in this process, China culture showed moderate openness and tolerance to different cultures in the opposition of "changing from summer to summer", and was able to develop and grow in the way of "changing from summer to summer". This undoubtedly has a strong cohesive effect on the unification and development of China's culture and politics.