A pioneering study in China focused on Xichang City in Sichuan Province, Southwest China, to examine the intersection of heroin use and HIV. The city has a population of 6 million and is located along major drug trade routes. China has faced significant drug issues since the economic shift in the 1980s. Due to proximity to the Golden Triangle, where much of Asia's opium originates, heroin is the dominant drug of choice, abused by 87.6% of drug users in the country. It is estimated that HIV has spread throughout the country, initially and largely driven by injection drug use (IDU).