And just like that, the Uygurs—with the complexity of their culture, the richness of their past, the fullness of their grievance against the Chinese state—fell into a tidy classification. China asked the United States to include a group of militant separatist Uygurs­ on its list of terrorist organizations but was rebuffed—at least at first.

In December 2001, 22 Uygurs were captured in Pakistan and Afghanistan, where they may have received weapons training with the intent of battling the Chinese military back in Xin­jiang. The men were rounded up by bounty hunters, handed over to U.S. forces, and sent to Guantánamo Bay. (Years later a U.S. court would order their release.) In August 2002 Deputy Secretary of State Richard Armitage traveled to Beijing to discuss, among other issues, America's upcoming mission in Iraq. While there, he announced a reversal in the U.S. stance: A militant Uygur group called the Eastern Turkistan Islamic Movement would now be listed as a terrorist organization.

The heart of Uygur tradition is the ancient capital of Kashgar. Today its Old City looks much as it must have when Marco Polo spied it after descending through the mountain pass—a warren of passageways and ancient mud-brick homes that resemble a jumble of oversize children's blocks. Early this year the Chinese government undertook a bold step: They began systematically bulldozing the Old City block by block and moving the inhabitants into a new compound on the edge of town.

Uygurs don't discuss the subject in public for fear of imprisonment, but one man who lives in the Old City, Ahun, agreed to talk with me in his home. A rendezvous would not be easy, because for days the Chinese security services had been following me. I was to wait in the main square during the busy midday until I saw him pass under Mao's statue, then follow at a distance without acknowledgment.

As we walked through city streets, he stopped casually to take a drink of water at a cart and later to tie his shoe. Finally we entered the Old City. The Chinese government's ostensible reason for demolishing the neighborhood is that it's too old to withstand an earthquake. But there may be another motive. As Ahun and I wove our way deeper into the warren, I watched his shoulders relax and his gait loosen. He was hard to trace in here. The Old City is a refuge.

The homes are adjacent and interconnected, and each is two stories high and arranged around a central courtyard. I followed Ahun up a flight of stairs, and when he flung open the door, it struck me that these homes are like oysters: On the outside they're drab and crude, but on the inside whitewashed plaster walls gleam, and many-colored rugs complement painted ceilings. "I pray. When I worship, I ask Allah, 'Rescue me my house,' " Ahun said. From his house he has a clear view of a government wrecking crew at work on a nearby home. According to the demolition schedule, they'll arrive at Ahun's home in three years.