秦汉帝国扩张的制约因素及突破口

The Constraints on the Expansion of the Qin and Han Empires and the Breakthrough Point

秦汉华夏帝国的疆域一度大举扩张。然至西汉中叶已无力推进,被迫收缩。汉代置而又弃的数边郡,标示了帝国扩张的极限所在。限制扩张的因素主要有三,其中前人忽视的因素是原住人群的政治体形态。规模较小的华夏式高级政治体最易被吞并;散居而无稳定政治体的山地人群最难被统治;两极之间尚有种种中等规模政治体,可借间接统治纳入帝国体系,最后可能变成正式郡县。南方山地多被平原上的华夏网络分割包围在网眼中,政治上破碎分立,只能形成中等规模政治体;山地经济的不自足性又使其依赖与平原地区华夏网络的贸易,无法远离帝国封闭生活。南方山地由此成为华夏帝国长期扩张的突破口。

The boundary of the Huaxia Qin and Han Empires expanded greatly at one point,but by the middle of Western Han the advance ran out of steam and the empire was forced to yield territory.Many border com manderies were set up only to be abandoned;they marked the outermost borders of the empire.There were three constraints on expansion.One that many scholars have previously overlooked is the political forms of the indigenous inhabitants.The small-scale Huaxia-style high-level polities had been quite easy to absorb,but scattered mountain populations without stable political forms were hard to govern.Mid-sized polities midway between the two could be absorbed into the imperial system and could end up becoming formal counties or commanderies.The politically divided mountainous areas to the south were caught in the net,surrounded as they were by the Huaxia networks of the plains.Politically,they were fragmented and could only form mid-sized polities;also,the fact that the mountain economies were not self-sufficient meant that they depended on trade with the Huaxia network of the plains and could not live isolated from the empire.Hence the mountainous areas of the south were the breakthrough point for the Huaxia empire's long-term expansion.