The Silk Road proposed by Richthofen mainly refers to a land passage between Europe and Asia (later called the Desert Oasis Road), which passes through the hinterland of Asia and is connected by oases in arid deserts, Gobi and plateaus. In the middle, each has its own way. For example, from Xi 'an, after passing through Hexi Corridor to Dunhuang, it is divided into three roads in Xinjiang, namely, South, Middle and North, in which the South and Middle Road meet in Kashgar and enter Central Asia after crossing the Pamirs. Through Uzbekistan, Kyrgyzstan, Tajikistan, Turkmenistan and other central Asian basins, it reaches the Iranian plateau and then reaches the Mediterranean coast. In fact, this route has been recorded in China's ancient book Biography of Sui Shu Pei Ju. Although there are differences, they are generally similar.