北魏六镇防线的空间分析

Spatial Analysis on the Defensive Lines of Six Towns in the Northern Wei Dynasty

北魏六镇是北魏迁都平城以后为加强北部边防而依次设立的六处军镇,在最初设立到不断发展过程中其经历了由"绥和服远"向"对外御夷"的职能转变。作为城防体系的一部分,它与六镇长城及其沿线戍城共同构成了相对完整的城防结构。本文以考古发现的六镇沿线城址为基础,通过地理信息系统对其进行空间分析,从水文条件、地形条件、视域条件、交通条件等方面探析了包括镇城、戍城与六镇长城在内的六镇防线在选址上的地理因素以及内部结构之间的相互作用,指出六镇防线设置的必要性。并且进一步揭示出北魏六镇防线的全面完善是其汉化政策推进的配套工程,其建立和完善是以北魏迁都和文化转型为内在动力的,对于北魏统治者自我认同的转变亦有象征意义。此外,本文还在前人研究基础上,通过地理空间相关分析进一步推测六镇各镇城的地望。

Six towns in the Northern Wei dynasty were built to reinforce the northern defense after the capital was moved to Pingcheng. Their primary setup was orientated to maintain peace through the policy of conciliation. Through continuous development, their function was later transferred into a defensive unit against exterior enemies. As part of urban defense system, the six towns constituted a relatively complete defensive structure with the local great wall and garrison towns altogether. Based on the archeology discovery of the town sites and their spatial analysis with the GIS, this article illustrates geographical factors of site selection including hydrographic, topographic, perspective and traffic conditions, explores the interactions between the defensive lines of six towns and the great wall, and points out the necessity of setting up the defensive lines. Furthermore, this article reveals that the comprehensive accomplishment of the defensive lines of six towns is actually a kind of auxiliary project accompanying the ＂＇assimilation into Han culture＂ policy of the Northern Wei dynasty. The establishment and completion of the defensive lines is driven by the cultural transformation and capital moving, which offers a symbolic meaning regarding the transformation of self-identification for the rulers of the Northern Wei dynasty. Meanwhile, the author also analyzes the locations of all six towns through geospatial analysis based on previous studies.