re: Was the Boxer Rebellion the most influential event in Chinese history?

The unification of China under the Qin dynasty had a large influence as well. IIRC it pretty much introduced the idea of a centralized, bureaucratic government under the control of a single authority (emperor/ccp). The Qin also introduced a lot of legal reforms, standardized writing, etc. That, and "China" itself supposedly comes from "Qin."