Before the discovery of the sea route to India, the Silk Road was the most important connection between the East and West. It experienced its last great era during the time of the Mongol Empire. This ancient trade route starts in the old capitals of Luoyang and Xian (then called Chang'an), reaches the Yellow River at Lanzhou, then skirts westward along deserts and mountains before dividing into three routes at the oasis of Dunhuang. The great part of the Silk Road threads its way through Xinjiang. Ancient travelers left behind many historical records and invaluable relics.