早在汉朝以前,北方的游牧民族就开辟了连接欧亚大陆东西两端的国际通道,被称为“草原之道”(Grassy plain route)。东至蒙古高原或阿尔泰山地,通过哈萨克斯坦,沿黑海西岸南下,一直到希腊本土。通道的大部分处在广大的草原地带,没有高山沙漠险阻,沿途有一望无际的茂盛水草,最适宜商队车马通过。到了汉朝,张骞经由内陆沙漠边缘,开辟了从沃洲通往西方的“沃洲之道”(Oasis route)。从此,大规模的商队都从草原之道转移到沃洲之道上来,十九世纪这条通道被德国地理学家李奇霍芬(Baron- As early as the Han dynasty, northern nomads opened up an international corridor connecting eastern and western Eurasia, known as the “Grassy plain route.” East Mongolia Plateau or Altai Mountains, through Kazakhstan, south west along the Black Sea, until the Greek mainland. Most of the aisles are in vast grassland areas, without the help of mountain deserts. There are endless lush aquatic plants along the way, and the most suitable caravan passes. In the Han dynasty, Zhang Qian opened up the Oasis route from Vaud to the West via the edge of the inland desert. Since then, large-scale caravans have shifted from Prairie Road to Wal-Mart Road, the 19th century this passage by the German geographer Li Qi Huo Fen (Baron-