DUNHUANG, CHINA - JUNE 8:  Chinese tourists ride on Quad bikes along the dunes in the Gobi desert on June 8, 2007 outside Dunhuang, China. Dunhuang was an important stop-over on the ancient Silk Road, also a strategic location on the trade route for the imperial court. Today, many tourists come here to ride on camels, sand surfing and trek in the desert. (Photo by Per-Anders Pettersson/Getty Images)