I was listening to a Japanese history book today and it occurred to me that I've never really heard of a Japanese or Chinese Bronze Age.
It made me wonder if the world all kind of got there at the same relative time through trade and war, or if other areas got there on their own at different times, or if any areas skipped any of these ages without interference from another culture.
I know it's not quite what you're asking, but my answer on when the Ban Chiang culture created their first bronze artefacts may be of interest. Essentially, Vietnam and Thailand seem to have entered the Bronze Age quite rapidly, probably because they had adopted bronze working from southern China, as opposed to a slow process of trial and error.