 The Mongols , a nomadic confederation , had unified in the middle of the twelfth century . They and other steppe nomads occasionally raided the Jin empire from the northwest . The Jin shied away from punitive expeditions and was content with appeasement , similar to the practices of the Song . The Mongols , formerly a Jin tributary , ended their vassalage in 1210 and attacked the Jin in 1211 . In light of this event , the Song court debated ending tributary payments to the weakened Jin , but they chose to avoid antagonizing the Jin . They refused Western Xia 's offers of allying against the Jin in 1214 and willingly complied when in 1215 the Jin rejected a request to lower the annual indemnity . Meanwhile , in 1214 , the Jin retreated from the besieged capital of Zhongdu to Kaifeng , which became the new capital of the dynasty . As the Mongols expanded , the Jin suffered territorial losses and attacked the Song in 1217 to compensate for their shrinking territory . Periodic Song raids against the Jin were the official justification for the war . Another likely motive was that the conquest of the Song would have given the Jin a place to escape should the Mongols succeed in taking control of the north . Shi Miyuan ( 史彌遠 ; 1164 – 1233 ) , the chancellor of Song Emperor Lizong ( r . 1224 – 1264 ) , was hesitant to fight the Jin and delayed the declaration of war for two months . Song generals were largely autonomous , allowing Shi to evade blame for their military blunders . The Jin advanced across the border from the center and western fronts . Jurchen military successes were limited , and the Jin faced repeated raids from the neighboring state of Western Xia . In 1217 , the Song generals Meng Zongzheng ( 孟宗政 ) and Hu Zaixing ( 扈再興 ) defeated the Jin and prevented them from capturing Zaoyang and Suizhou . 
