Alvin,
That’s a fairly easy question to answer.
The Red Nine C96s were all Imperial (and later Weimar) German Army property. Those Imperial contract 9 mm C96 pistols not converted to comply with the Versailles treaty were collected and destroyed. There simply weren't many Red Nine C96 pistols available to sell China.
The vast majority of C96 pistols that ended up in China were pre and post Great war commercial production sold commercially (via Japan factors)to buyers in China. DocSkunk’s gun is a good example of one of the pre-war commercial guns procured for sale in China.
The pre-WWII Chinese market for handguns chambered for the 9 mm Luger cartridge was almost non-existent because the 9 mm Luger cartridge was largely non-existent in China at that time. It was not until the second world war, and the attempt by England to introduce the Inglis Variant of the Browning P.35, that any significant amount of 9 mm Luger ammunition became available in China. Not that even then the attempt to introduce the Inglis to China was not a big success with most of the pistols actually sent to the Far East ending up in India.
The relative scarcity of 9 mm Parabellum ammunition, along with the plentitude of 7.63x25 Mauser, is why we never see any C96s produced in China (like the Hanyang, in the slide show link below) chambered for the 9 mm Luger:
http://s295.photobucket.com/user/Kyr...g%20C96?sort=9
Best,
Kyrie