From the dawn of civilisation to the Qing dynasty China has held a majority of the world's population; what stopped the Chinese people from expanding westward or committing itself to becoming a global empire like many European ones? Or more, why has it long (seemingly) approached a way of isolationism?
The important thing to note is that China (or rather, powerful dynasties e.g. Tang, Ming, Qing) were world powers as they were, without any further westward expansion. And there's only so much territory and so many people one can rule over without suffering the effects of an overextended empire (before the telegraph and railroad at least). The Qin dynasty for example (considered the first Chinese imperial dynasty) only lasted 221-206BC, 12 years of which it spent unified, as it followed a governance system suited for military conquest (where it performed well) but not peacetime governing, thus the empire fractured. Which brings up the fact that China was not unified from the dawn of civilization to the end of Qing, there were long periods of many Chinese kingdoms fighting each other which naturally makes large-scale expansion somewhat difficult.
The Tang dynasty (618–907) expanded all the way to the Aral Sea (westward expansion happened here) as they were eliminating the threat of nomadic tribes and subjugating neighbouring states. Southern China, like the Guangzhou region, became a trade-heavy region, with foreign merchants settling in China and Chinese merchants trading with far-away lands.
The Ming dynasty (1368-1644) was certainly a world superpower, at least in its early times, centralizing the state, strengthening the army and navy to impressive numbers and forcing neighbouring states to pay tribute to the Ming emperor.
The Qing dynasty (1644-1911), a China ruled by non-Chinese (impressive in its own right) was the largest and most populous dynasty, setting the general borders of modern China, continuing the tribute paying tradition (e.g. they exercised great influence in Korea until the first Sino-Japanese war in 1895), ruling over Taiwan in a very colonial-empire-like way and taking the heavy fire of European expansion into China.
I am a simple wiki-warrior, send assistance
For the progress of China becoming isolated and inward oriented, to my knowledge during the end of Ming and the reign of Qing, as well as the comparison of the conditions necessary for the idea of over-seas colonization to arise in Europe and China, someone else might want to fill in. They're massive intimidating topics and I'd rather not end up in badhistory.