For most Westerners, Chinese are all of the same race. In fact, there are profound ethnic differences that can easily mutate into open conflict and war. An example is the Punti-Hakka Clan Wars (Chinese: 土客械斗) in Canton in 1855 that lasted a decade. The war's estimated death toll was roughly a million, with many more fleeing for their lives. Hakka means immigrant and Punti means native. The same type of ethnic resentment survives in Taiwan and in Fujian Province.
I believe that this chronic internal divisions make China such a tempting target for imperialists.