The dry, salty desert soil kept this mummy in extraordinary condition for thousands of years.

In the far west of China, archeologists have made some extraordinary discoveries. The arid landscape of the Xinjiang Province perfectly preserved the bodies of people who died there as long as four thousand years ago. These mummies, along with their elaborate garments and personal artifacts, paint a detailed, sometimes surprising picture of world history- one today's Chinese government is sometimes reluctant to accept.

In "Time Travelers," FRONTIERS is the first TV crew allowed to film these mummies. While their level of preservation is remarkable, what is perhaps most striking is that the mummies do not appear to be Chinese. Their prominent noses are clearly Caucasian features, suggesting these people came from the west. Their fine wool wraps, braided cord, felt bedding, along with items like a leather saddle and a cow horn drinking cup all closely resemble the culture of the modern day Kazaks, to the west of China.

Chinese archeologists clean and examine the mummies for insect damage.

University of Pennsylvania scholar Victor Mair is largely responsible for putting these mummies, and the debate over their origins, in the spotlight. He believes they represent ancient western people who brought to China new technologies, like the wheel or bronze, for which the Chinese have long been credited. Official China disapproves of Mair's ideas, not least because they may encourage the separatist movement of Xinjiang Province's Uyghar people, who are themselves not Chinese.