The Chang Feng is named for the company that developed it, the Chongqing Chang Feng Company Ltd in (you guessed it) Chongqing. It was designed by one Qing Shangsheng, who had ample prior firearms design experience (including the Type 64 and 67 pistols and Type 80 SMG). The design is based around a helical magazine inspired by the Russian Bizon and the American Calico. Early patterns used the magazine as a buttstock, but it was moved up on top of the weapon. The early versions were also chambered for the Chinese 5.8mm pistol cartridge before being changed to 9x19mm to better suit an export market.
The final production version included a threaded muzzle device for suppressor use, a rear-mounted rail for a variety of optional optical sights, and a telescoping stock. It was sold to a number of Chinese security agencies as well as being exported to Myanmar, Venezuela, and Uganda.
Many thanks to the French IRCGN (Criminal Research Institute of the National Gendarmerie) for generously giving me access to film this very rare specimen for you! They maintain an extensive firearms reference collection as part of their mission to fight crime and international terrorism.