China has greatly increased its mutual legal assistance treaties with other nations in recent years. It now has such bilateral treaties with 20 countries, and extradition treaties with three nations. There is no strong evidence of heroin production in China, but it produces limited amounts of opium, mostly for domestic consumption. PRC officials estimate that most of the illicit opium seized in China is smuggled in from Burma, while only about 10 percent originates in China. In addition to cultivation in the provinces bordering the Golden Triangle, smaller amounts of opium poppies were reported in the Northwestern Province of Ningxia.
Most heroin entering China is produced in Burma, near the Chinese border.
However, some of the opium smuggled into China comes from Vietnam. Traffickers usually bring in heroin through Yunnan province. Some shipments move directly across the Sino-Burmese border, and some enter southeastern Yunnan from Vietnam. A portion of the Golden Triangle heroin of uncertain origin flows into Guangxi Province from Vietnam. The PRC encourages citizens to report on possible cases of drug smuggling and use.