GuoDa is a good partner. It is the biggest player in an extremely fragmented market, with 2.7 percent market share in 2015, according to analysts at Guotai Junan International. It is also growing fast: as of June it boasted 3,693 stores, up 13 percent in a year. And it is backed by China's leading distributor, the $11 billion Sinopharm Group, which is state-controlled but listed in Hong Kong.