从汉中东三郡的政区建置看魏国战略目标的调整与实现

汉献帝建安二十年（215），曹操平定张鲁、据有汉中，随即按照山川形便将汉中分置为四郡，相对于汉中盆地所在的汉中郡，位于东部西康盆地和鄂西山地的三郡被称为东三郡。在魏、蜀对汉中的争夺中，东三郡一度随汉中入蜀，又因孟达叛蜀而再度入魏，此后一直为魏所据。东三郡僻处秦巴山地，由于地形复杂、交通不便，其战略地位并不突出，但作为同时邻近蜀、吴两个敌人的边境区域，东三郡又非无足轻重，孟达的反复更加剧了东三郡的复杂形势。魏国在东三郡频繁的政区建置及其在行政区划史上的影响，在一定程度上反映了其区域战略目标的调整与实现。

Strategic Planning of Wei State in East Hanzhong:A Perspective of Administrative Regionalization of the Three Prefectures

After Cao Cao occupied Hanzhong after suppressing Zhang Lu in 215,he immediately divided the Han River Valley into four prefectures (known as 'Jun') according to topographical features.Compared to the Hanzhong Prefecture which was located in the Hanzhong Basin,the other three ones,which were east of Hanzhong and were located in Xikang Basin and Exi mountainous area,were referred to as 'East Three Jun'.During the fight for Hanzhong between Wei and Shu States,East Three Jun was once occupied by Shu State for a short period and soon returned to Wei State again due to a general of Shu State—Meng Da's betrayal.Bordering on two hostile states in the west and south,East Three Jun held an important strategic position though its geographical and traffic conditions were a hinderance to military operations.Wei State,therefore,frequently regulated the administrative regionalization in this frontier area and sophisticatedly adapted to the changing situations.In this manner Wei State was able to achieve its strategic targets in this region,both in military affairs and to some degree in local development.