This is true now. But before, most people would have been loyal firstly to their area, speak a (quite possibly non-Chinese or even Sino-Tibetan) language or dialect only understood in their area, and at would at most have heard the names of some far-off places. It was not that different to Europe. And that's the relatively Chinese areas. Don't forget also that up until the 20th century large areas of present-day China were demonstrably not Chinese, in that nobody could speak or read Chinese in the area and they had adopted virtually zero Chinese language or culture.
I get where you're coming from. I think what the article should have said was, Europe has geography that favors multiple independent stable nation states, whereas Chinese geography, while it has certainly hosted many competing dynasties over the centuries, does not favor multiple stable nation states. Basically, it's too easy to conquer the whole, so it's been done many times.
Yes, if only the major rivers in China were different...
The Yellow River and the Yangtze River systems are so close that it isn't realistic to have long-term control over one and not the other. And controlling both gives you a fantastic base from which to conquer your surroundings.
