The People's Republic of China is a large nation-state on Earth located in the eastern portion of the Asian continent.
Stargate Command had worries about this nation and Russia discovering the existence of the Stargate. Ultimately, Major General George S. Hammond and Major Paul Davis informed the Chinese government, via an ambassador, of the existence of the Stargate in 2003. (SG1: "Secrets", "Disclosure")
It is noted in several instances that China is very uncomfortable with the United States Air Force's unilateral control of the Stargate; more so than any of the other nations involved in the program. In 2006, China supported a Russian demand for the return of the secondary Stargate; however, this turned out to be nothing but leverage to acquire a Daedalus-class battlecruiser. Thus, the Stargate remained in American hands. (SG1: "Crusade")
In ancient times, China was ruled by the Goa'uld Yu. A Tau'ri general named Sun Tzu was alive during this era and wrote the Art of War, a famous book on military strategy. Yu was so fond of Sun Tzu that he made him a member of his Royal Guard and cloned him several times, the final clone acting as his First Prime. (SG1: "Fair Game", "Summit", "Four Dragons")