Before and after the demise of the Western Jin Dynasty, what years were the last years of the Western Jin Dynasty mainly concentrated because of population migration? Shi Shicheng

Concentrated in the Yongjia period of the Western Jin Dynasty, it was known as "one pass of Du Nan". This is the first time that the Central Plains regime and civilization moved southward, from Luoyang, the capital of the Western Jin Dynasty, to Jiankang (now Nanjing). During the Western Jin Dynasty, during the reign of Emperor Huaidi and Xu Di, a large-scale war continued in the Central Plains, and neighboring tribes who migrated one after another established a monarchy, which was powerful and threatened the Western Jin regime, eventually leading to the disaster of Yongjia and the threat to the central court. During the period of Jin Jianwu, Emperor Jin Yuan led the Han people in the Central Plains to cross the south from Luoyang, the capital city, which was called "Yongjia Rebellion, taking the crown to cross the south". This is the first large-scale southward migration of Han people in Central Plains. After crossing the river in the Western Jin Dynasty, its capital was Jiankang (now Nanjing), which was called the Eastern Jin Dynasty in history. The gentry of the Han nationality fled south with other subjects in the Central Plains, which is called "Yongjia Rebellion" in history. Wang Dao relied on the northern gentry of Nandu to unite with Jiangdong strongmen to help Si Marui establish the Eastern Jin regime.