A "Greater China" trade Bloc?

Over the 1980s, trade between China and Hong Kong, and between Taiwan and Hong Kong has been increasing rapidly. The three economies appear to trade three times as much as a random trio of economies in the world even after we take into account their economic size, per capita GNP and geo-graphic distance. But this does not necessarily impl of the extra trade is due to the fact that they all speak Chinese. Another part results from the political reality that the trade between China and Taiwan has to be rerouted through Hong Kong (or other third countries). Once we control for all these factors, the trade among the three economies no longer seems unusually high.