中国历代王朝,对外防御或进攻,分若干个战略方向。为对付北方游牧民族南下,向北一般是战略防御方向;向西新疆(古西域)、中亚方向,历来是中原政权的主要战略方向,强盛时取攻势,衰弱时取守势;向南对岭南诸国,一般取攻势。东亚朝鲜半岛方向,因战略纵深不深,面积不大,人口不多,经济落后,内战不止,对中央政权威胁不大。理应不是主要战略方向。可是在历史上, Chinese dynasties, external defensive or offensive, divided into several strategic directions. In order to deal with the nomadic tribes southward from the north, it is generally a strategic defensive direction to the north. In the westward direction of Xinjiang (ancient western region) and Central Asia, it has always been the main strategic direction of the Central Plains regime. Countries, generally take the offensive. As the direction of the Korean Peninsula in East Asia is not deep because of its depth of strategy, its area is small, the population is small, the economy is backward, the civil war is more than a threat to the central government. It should not be the main strategic direction. However, in history,