The Democratic Chinese Alliance (中国民主联盟） is "Southern" China or all territory South of the Yangtze River with the exception of a divided Hong Kong. The DCA is the pro-democratic element of the People's Republic of China after its division in 1990 (TSR EP03). While the exact reasons for cessesion are not outright stated, they were probably inspired by the Tianamen Square protests of 1989 which was violently put down by the People's Liberation Army. After a period of five year warring, in 1995, both factions created a ceasefire that divided Hong Kong into occupation zones similar to East and West Berlin. By the time of TSR (1998) both factions began negotiating extension of this ceasfire. Both United States and Soviet Union deeply wish both factions to reunite and heavily back Mithril to allow a peace process to continue, while Amalgam seems intent of derailing the process and resuming the Civil War (which Gates himself says had a hand in it since the beginning.) After Amalgam is stopped in Hong Kong, the fate of both PLC and DCA and China itself is unknown.
The DCA operates primarly American technology, its mainstay Arm Slave (as seen in Hong Kong) is the M6 Bushnell and its soldiers use what appear to be weaponry of foreign origin, this may imply that the Republic of China (better known as Taiwan) had a hand in the DCA, if not part of the alliance. Or the U.S. supplied arms to the DCA. Standard soldier attire is of a richer green hue, and more similar to standard Battle Dress Uniform.