The Qing dynasty was a significant historical period for the stabilization and development of China’s territory. During this period，as the administrative institutions of northwestern regions were gradually optimized and the transportation system began to take shape. In addition to the "Gaolan Official Route，”which linked the capital with the northwestern region，there were also routes in the north that ran along the Great Wall to Beijing and to outposts in Suzhou and Jiuquan. The opening of these transportation routes enhanced trade between the northwestern and southeastern regions, and thus a unified and normative market system，dominated by official trade，developed in the early Qing dynasty. A center for transporting and trading tea, clothing, foodstuffs, furs from northwestern regions and medicine took shape，with Xi’an，Jingyang and Sanyuan as the manufacturing and transporting center of national commodities, Lanzhou as the secondary sale depot, and Xining, Hami，Ningxia and Gucheng as the tertiary wholesale markets. This market system became more stable after Qianlong emperor’s reign due to the weakened influence of official trade and growing power of merchants. This trading pattern did not change until the opening of treaty ports，the operation of trains，and the intervention of Western firms in modern times. The economic integration of the five northwestern provinces further facilitated the integration of regional administrative system. Based on this economic integration，the administrative plan of China took the five northwestern provinces as an integrated area in the early period of People’s Republic of China.