Some Uygurs found opportunity in the influx. In the 1980s in burgeoning Urumqi, a laundress named Rebiya Kadeer grew her business into a department store, then built that into an international trading empire. She became one of the wealthiest people in China and an inspiration for her compatriots—a Uygur woman who appeared in Asia's Wall Street Journal and met with such businessmen as Bill Gates and Warren Buffett. In many ways she seemed emblematic of Xinjiang: In the last two decades of the 20th century the region's GDP increased tenfold.

But many more Uygurs languished. The big business in Xinjiang is oil, but all that oil is controlled from Beijing by state-owned energy companies. Many of the good jobs in Xinjiang are government jobs, and employees can advance more readily if they join the Communist Party, which requires renouncing their religion. And most Uygurs won't do that. The result is an ironic and combustible symmetry: As Han settlers pour in, Uygurs, unable to find work in their fantastically wealthy and spacious homeland, migrate east to work in privately owned factories in crowded coastal cities.

In the past few decades local resistance has flared up around Xinjiang, fluctuating in scale and violence. During the 1980s Uygur students protested treatment by police in a handful of incidents; in 1990 a disturbance south of Kashgar against birth limits ended in perhaps four dozen deaths. In 1997 hundreds of people in a city called Gulja marched to protest repression of Islamic practices and were arrested; the number of casualties is unknown. Other examples abound, including bus bombings and assassinations.

The Chinese government realized that it had a problem in Xinjiang, much as it had a problem in neighboring Tibet. Along with regulating mashraps—those traditional gatherings—the state monitored services at mosques, afraid they might provide a platform for dissidents. In general, officials downplayed the unrest as the work of isolated "ruffians" in a Uygur population that was otherwise blissful. In early September 2001, Xinjiang Communist Party Secretary Wang Lequan announced in Urumqi that "society is stable, and people are living and working in peace and contentment."

A few days later Beijing received a potent and unexpected propaganda tool: September 11.

As America and much of the West launched the "war on terror," China recognized the momentum of global public opinion and chose a new tack. The shift happened so fast it came with an almost audible crack. On October 11 a spokesman for the Chinese Foreign Ministry described China as "a victim of international terrorism." Then the government issued a report on unrest in Xinjiang blaming none other than Osama bin Laden. "It's an effective strategy," says James Millward, a professor at Georgetown University and an expert on Xinjiang, "because in America we see Muslims somewhere who are unhappy and maybe even violent, and we assume it's because of religious reasons."