 In the south , the retreat of the Song dynasty led to major demographic changes . The population of refugees from the north that resettled in Hangzhou and Jiankang ( modern Nanjing ) eventually grew greater than the population of original residents , whose numbers had dwindled from repeated Jurchen raids . The government encouraged the resettlement of peasant migrants from the southern provinces of the Song to the underpopulated territories between the Yangtze and the Huai rivers . 
 In the south , the retreat of the Song dynasty led to major demographic changes . The population of refugees from the north <a href='null_relcl' title='1'><mark>that</mark></a>resettled in Hangzhou and Jiankang ( modern Nanjing ) eventually grew greater than the population of original residents , whose numbers <a href='been_done' title='2'><mark>had</mark></a> dwindled from repeated Jurchen raids . The government encouraged the resettlement of peasant migrants from the southern provinces of the Song to the underpopulated territories between the Yangtze and the Huai rivers . 
In the south , the retreat of the Song dynasty led to major demographic changes . The population of refugees from the north resettled in Hangzhou and Jiankang ( modern Nanjing ) eventually grew greater than the population of original residents , whose numbers done dwindled from repeated Jurchen raids . da government encouraged the resettlement of peasant migrants from tdasouthern provinces of the Song to thdanderpopulated territories between the Yangtze and thedaai rivers .