There have been many remarkable feats of human endurance over the centuries. The early trade routes between the east and the west would undoubtedly rank among them. They covered some of the most inhospitable parts of the earth, with searing deserts and blinding sandstorms, to frozen high mountain passes.

That was then. This is now. In 2010 there is a four-lane divided highway most of the way from Xi'an to Kashgar. The few bits that don't have it soon will. Tourists step out of air-conditioned buses through turnstiles into theme parks that in some cases are beginning to resemble Disneyland, with everything from concrete camels to coloured lights, and the inevitable souvenir shops. There were times that I wished I'd done this trip twenty years ago.