Ancient China grew up from a hodge-podge of independent city States primarily along the Yellow River. In addition to the Han Chinese population, there were other, different peoples and cultures there as well. Eventually, of course, the whole country was unified under the First Emperor. But what if it hadn't been, and what if no other dynasty is able to unite it for more than a few years throughout it's history?
The territory of China is huge, and on the face of it, would seem large enough to support a network of independent states, each with its own language, culture, government, system of writing, weights and measures, currency, etc., such as existed in Europe. How could this be achieved?