Yeah, that was put forward as an explanation, but I never bought it.
I can see how geography had an impact on the political structure of China. The logistical and military details of trying to defend a portion of China is very difficult. It's too easy for some "hoarde" to sweep the whole area. So it's an all or nothing kind of proposition ... i.e. either you develop the power to control it all or you lose it all.
And of course geographical references make their way into the cultural fabric, but that's true of any culture. The Scots love poems about heather and the Pacific Islanders love poems about the sea. That's not unique to China.
But why is their religious outlook so unique? Why would a Japanese mountain become holy whereas a Chinese mountain is just a mountain. Being a westerner, I'm not sure I can express it well. The best way I can explain it is that the Chinese religion is "secular," which sounds odd, but it's basically true. It has its mystical aspects (the word that comes to mind is "superstition" but I don't mean it in a derogatory way), but there isn't really any deistic component to it. Yes, the emperors sometimes called themselves "gods", but the view of that was different than when the emperors of other cultures used that term. It was more an idea of unquestioned honor and respect than of immaterial power.
Confucius reigns supreme in Chinese philosophy, and you might call him the world's first pragmatist. Yes, there is also Daoism and so forth, but even that is more an aesthetic secularism that provides the yang to the Confucian yin rather than the spiritual blather that western expatriates hang on it.
In fact, now that China has been influenced by the west (and by Buddhism) I'm not sure we'll ever really know what the original Chinese philosophers actually meant. Everyone will have their own idea, and who is to say what is "correct." My impression was that they didn't believe in anything immaterial - no deity, no spirit, no mystical things. Rather, they believed that the material itself is of such complexity that it will never be understood, and so it is within the material that there are things of mystery and power. In the end, those two words seem the best summary to me - that while other world philosophies had their root in the mystical, Chinese philosophy had its root in the mysterious.
But as to how that difference occurred, I have no idea.
