From Zhongdu(Yanjing)to Nanjing(Bianjing):the Final Ruin of Jin Dynasty

The force of Mongolia, since its rising abruptly in the Mongolia grassland in the early days of the 13 rd century, started to advance to the south to attack the district controlled by Jin Dynasty and compelled from pace to pace with the strength growing gradually.And at this time Jin Dynasty fell in decline due to the change of instiution systems,the degeneration of military competence and the corruption of the spirit in official circle.The falls of Zhongdu in 1215(Zhenyou 3 rd year of Xuanzong reign in Jin Dynasty)and Nanjing in 1233(Tianxing 13 nd year of Aizong reign in Jin Dynasty),became the important landmarks of the last more than 20 years in the process to go downhill.