Migration and identity are tough issues, particularly as our tendency towards literalism (you thought we were all postmodernists? Not even close.) with regard to concepts like nation and ethnicity continues to grow. Using Nationmaster, Sun Bin produced some lovely maps of the Chinese Diaspora. My only big quibble is the lack of data for the Russian Federation, given the thousands of Chinese in the Russian East before the PRC and particularly in the present. Still, it's a fantastic example of the ease with which data and imaging tools can produce fantastic graphics.
A while back, I ran across this critique of media coverage of Taiwan [via] from Michael Turton (a fantastic Taiwan-based blogger, with lots of links and interesting things to say, including a regular roundup of Taiwan blogs that looks like a great resource) which actually illustrated for me this tendency to literalism quite strongly. In this particular post he actually argues that "China has never owned Taiwan" largely because Taiwan was "never the possession of any ethnic Chinese emperor." In other words, the Qing dynasty which conquered Taiwan and which was the acknowledged possessor of it in international law (up to 1895, when the Japanese got it as part of the Sino-Japanese war indemnity), doesn't count as Chinese.
From a strictly literal ethnic point of view, and based on thoroughly modern concepts of international law, there's some grounding to that: the Qing dynasty was Manchurian in origin, ethnically distinct and based on conquest. Though Qing emperors lived very typical Chinese Imperial lives, throughout the Qing, the government was deeply concerned that non-Manchu Chinese would discover some ethnic solidarity or identity (Kuhn's Soulstealers is a good example, from mid-dynasty) and there's no question that part of the fall of the Qing was related to irredentist Han nationalism. But that's a very late development; there's about two centuries of the Qing dynasty in which nobody seriously questions the legitimacy of Manchu rule. If the Qing isn't legitimately Chinese, then the modern borders of China -- based on Qing conquests -- need serious reconsideration, particularly in the west.
But the "strictly literal ethnic" and "thoroughly modern concepts of international law" are absurdities when applied that far back or that literally. While I'm sympathetic to Turton's position on Taiwanese independence, applying the same principles would delegitimize its current government -- based on ethnic migration and conquest -- and probably (since Turton seems to acknowledge Japanese colonization) result in US control of the island. More to the point, it presumes an historical purity which runs counter to all experience.
Non Sequitur: a bibliography of Chinese popular religion scholarship