A Study On The Distribution Of Towns In Hexi In Early Tang Dynasty

The layout of towns located in Gansu corridor is affected by many factors. For the nature,the narrow corridor laies between two mountains in south and north,the rivers which originate from Qilian mountain present a south-north torwards flowing direction that made the towns' distribution being similar with oasis's as a result, construct a main town agglomeration named Anxi channel from the east to the west in the corridor.the most important towns and settlements always settled in from the four hexi counties established by han dynasty.The north of the Gansu corridor were controlled by the powerful nomadic groups in the early Tang dynasty,the Tibetan rose in the south from Tibetan plateau and occupied the Huangshui area, middle kingdom lost the way lead to Tibetan Plateau which called steppe channel and Tuyuhun channel, made the Anxi channel became the most important, in order to defense Tibetans and cut the nomadic connections off, kept stability of corridor towns as well, Tang governments had settled many military units call Zhuo,Jun, Zhen, Shu in the five important passageway from Qilian mountain to Tibetan plateau, with those affairs, the middle kingdom can control these north-south channel to ensure the army provisions transporting and protect the towns from the nomadic's attacks, ensure the safety of silk road as well. Finally, these military settlements and counties makes a Gansu corridor's town system, it is a compositive one that contains the transporting affairs and the military affairs.