长三角,即长江三角洲地区,狭义上指南京、苏州、无锡、常州、扬州、镇江、南通、泰州;浙江的杭州、宁波、湖州、嘉兴、绍兴和舟山等十多个地级市及上海。长三角地区虽然面积狭小,人口在全国所占比重不高,在历史活动中却一直十分活跃。西晋末年,北下流寓人口增 In the Yangtze River Delta, the Yangtze River Delta refers to more than a dozen prefecture-level cities such as Hangzhou, Ningbo, Huzhou, Jiaxing, Shaoxing and Zhoushan in Shanghai and Shanghai in the narrow sense, referring to Nanjing, Suzhou, Wuxi, Changzhou, Yangzhou, Zhenjiang, Nantong and Taizhou. Although the Yangtze River Delta is small in size and its population is not high in the country, it has been very active in historical activities. In the late Western Jin Dynasty, the population in the north was increased