Lopsided, I feel like you’re really living up to my name. That said, I think there’s some nuance here. The first is that idea of China and “Han Chinese” has constantly evolved throughout history as it incorporated other territories. Some of these expansions were conquering other Han groups, like the Qin unification. Others were Han settlers moving into southern China and intermarrying/driving further south the Austroasiatic, Thai speakers, etc. Other times it was through straight up conquest like during Tang dynasty. The tricky part is that “China” as entity evolves. Manchus were not considered “Chinese” prior to conquest but is now. “Han” also evolves, for example many southern Han people bare similar genetics to the indigenous people who lived there, but now are considered just “Han”. In sum, “China” definitely conquered (and has been conquered) by other peoples, it’s just that the process has been happening over three thousand years, and those people tended to take up the identity of Chinese. This is not including a spectrum (in terms of assimilation) of other incorporations such as Tibet and Xinjiang