古代的北京,我们已在前几篇中分析过,由于它的特殊地理位置,成为北方军事重镇、北方商业中心和南北交通枢纽。在这一历史时期,古代北京又显出了它的两个特点:当中央政权力量衰弱时,它就常常成为军事割据势力的中心之一;当中原政局混乱时,它就往往成为北方游牧民族南下的主要据点之一。在东汉政权衰落消亡、群雄并起、三国到 In ancient Beijing, we have already analyzed in the first few articles that due to its special geographical location, it has become a military center in the north, a commercial center in the north, and a transportation hub between north and south. In this historical period, ancient Beijing showed its two distinctive features: when the power of the Central Government is weak, it often becomes one of the centers of the forces of military separatism. When the Central Plains politics was disrupted, it often became a nomadic northern nation One of the main locations south. The decline and collapse of the regime in the Eastern Han Dynasty, the democrats and the three countries arrived