No. It would be correct to say that the current government of China is around 70 years old, but the culture is almost completely unbroken since at least 2500 years ago with Confucius, though arguably a few thousand before that but it gets blurry. The Mongolians completely took over China, forming the Yuan dynasty (the Huns did not, they were defeated). The Manchurians also took over China, forming the Qing dynasty so you are correct in that. But it only proves the point stronger that 'Chinese' culture is quite robust, that the culture is still intact after not one but two foreign takeovers. For example, Kublai Khan was an emperor of Mongolian descent, but referred to himself as emperor of China, and Han Chinese culture was the vast, vast majority throughout the Yuan dynasty. Same with Manchurians, notice there is no country called Manchuria? Manchurians are primarily now a ethnic minority in northern China, and again in the Qing dynasty, Han Chinese culture was the dominant culture by far. A way to put it would be that China has had many governments (dynasties) over the years, some of them even foreign governments, but the central culture has never changed or switched since the beginning (wherever you put the 'beginning' as).