Analysis: China Takes Over the World
Like more than a few other ... questionable tropes in this vein, this has some (emphasis on some
) grounding in history
The reason why the South and East China Seas are called that (and why those names are liable to trigger an Internet Backdraft when mentioned on more than a few Vietnamese, Filipino, or Korean forums) is because they marked the traditional realms of Chinese influence, as their shipbuilding more or less dwarfed everybody else's until the Japanese Westernized in the late 19th century.
Their land military was also in no way not a force to be reckoned with, though the neighboring nations had better luck with it than they did the navy (for example: see the original Tet offensive or the disastrous Sui invasions of Korea)note
. As result, China could generally push around every other nation in the neighborhood in a way no European power (even Rome) ever could, and often forced them to swear allegiance to the reigning dynasty of the time (a major objective of Zheng He's famous voyages), to the point where on paper the far East generally consisted of "China" and "Chinese Tributaries." Of course, the tributary status was generally a joke unless enforced (which generally was not done save for those that were extremely close, like Korea) and even then they realized on some level there was land outside of that under their control. This lasted more or less until the West came knocking and China more or less imploded on itself and spent the next decades rebuilding.