I would say geography and climate are the dominant factors in developing civilizations and cultures. It dictates where and how populations may live, the carrying capacity dictates what size populations are sustainable, and rivers are the arteries of trade and culture that both define and bind together economies and peoples. I find that governments most often develop around economic systems and factors, rather than the other way around.
Geography and climate are the initial shaping forces in the development of any new civilization. Rivers are starting points for any major settlement in any part of the world because they provide easy transportation of people and goods as well as irrigation for agriculture through flooding or canals. If the climate is suitable for the development of agriculture, allowing people to settle rather than continue as nomads following game and native edible plants through the seasons, the settlement will take root and grow accordingly. Part of that growth process will then be the development of a barter economy among the different people who have different goods or services to trade, and the development of rudimentary government as the growing group of people figures out the basic rules of conduct they need with respect to each other.
Post 3 notwithstanding, China has been relatively unified for much of its history. This can be connected to its river systems and its relative lack of barriers to travel and trade even between the two systems.
China has two major east-west rivers. Products and people could always move relatively easily along each river. This helped to develop China's economy and unify its political system. In addition, there were no major natural barriers to travel between the two river systems. This made commerce easier and also allowed political domination to spread over much of what is now China.
China's geography definitely influenced its development. For one thing, China is a huge area. Many parts of it are remote and inaccessible. This is one of the reasons that so many different dialects developed. China was so large that it was basically more than one country.
As with the case of Egypt and India, early Chinese civilization was a river civilization, based primarily on the Yellow River which flooded and deposited soil which could be planted. The flooding was very arbitrary and capricious and often was quite damaging, so much so that The river was frequently called the "river of sorrows." The rich topsoil, known as loess, made agriculture profitable. Successful agricultural practice made the development of settlements along the river possible.
The influences of the river and the agriculture it made possible were infinitely more important in the development of China than governmental or economic developments. The ability to produce an surplus of crops led to specialization and the development of settlements and from their stratified societies.
The link below can provide you with more information on Ancient China