I think it may have a lot more to do with the ability to communicate across the country. In the past, their language differences didn't seem to be a hinderance to governing the people because transportation wasn't that good either (except along the major rivers) and backward enough among the masses that the main question about government might be: "What's a government?" As communication and education of more people improved, so did the questions, which mandated making up the truth to appease and of course a massive army to control them. I think their form of government will prevail as long as it is needed for control and if the government changes, so will the boundaries and there will become many Chinas.

I'm currently reading the book '1421 The Year China Discovered America' by Gavin Menzies and am amazed at the strength of their navy and extensive ships and sailing methods. Compared to them, Europe had nothing but yet was able to colonize because of the later ban on sea travel.

Peace