唐安西四镇中"镇"的变化

安西四镇的称谓,自安西都护府迁到龟兹后,就已出现。此后,曾三次陷落于吐蕃,四镇三失三复的重要教训是,要保持对四镇的稳定统治,必须要派驻足够的兵力驻防才有保障。长寿二年(693年)朝廷决定用汉兵三万人以镇之。此后,在安西四镇之下,又增设了许多二级军镇,除碎叶镇外,还有如拨换镇、通海镇、葱岭镇等。于阗镇下增置有坎城、兰城、胡弩、固城、吉良等五个二级镇,在于阗镇内诸州,还设置了州级军镇,如六城质逻州的杰谢镇,还有安夫镇,实为三级军镇,玉河军、箫乡军,也可能属于阗镇辖下的军镇名。在于阗镇内设置如此众多的军镇,主要是为了对抗吐蕃对于阗、进而对四镇的进犯。众多新军镇的建置,是唐安西都护府发展史上的一个重大变化,也是唐对西域统治由不稳定走向稳定的重要保证。

Changes of "Zhen" (Garrison Command) in the Four Garrison Commands of Anxi during the Tang Dynasty

The name "four garrison commands of Anxi" appeared after the Anxi Frontier Command was moved to Kuche. Later, the four garrison commands fell into the Tubo's hand three times. The important lesson drawn from the three-lost-and-regain of the four garrison commands is that only sufficient troops were garrisoned there could the four commands be safe and stable. In 2nd year of Changshou (693 AD), the court sent 30,000 soldiers to guard the four commands. Then many subordinate commands were set up under the four garrison commands of Anxi, for example, besides Suiye command, there are also Bohuan command, Tonghai command, Congling command, etc. Under Yutian command, there added 5 sub-commands, namely Kancheng, Lancheng, Hunu, Gucheng and Jiliang. Furthermore, in every sub-prefecture of Yutian command, sub-prefecture-level garrison command was set up, such as Jiexie and Anfu commands, they were actually third-level garrison commands, Yuhejun and Xiaoxiangjun might be the names of garrison commands affiliated to Yutian command. The aim of so many garrison commands set up in Yutian is to defense the Tubo's invasion of Yutian and further, of all four commands of Anxi. The set-up of so many new garrison commands indicated a significant change in the development of the Anxi Frontier Command in the Tang dynasty and enabled the Tang court exercised a stable rule in the Western Regions.