(2) The popularization of Zhancheng rice made the south of the Yangtze River the main food supply place in China, and the main economic source in Song Dynasty depended on the south.

(3) The economic center of gravity moves south.

(4) There are many wars in the north and relative stability in the south.

Northerners moved to the south, which increased the population of the south, increased the labor force in the south, and brought advanced production technology and tools.

Jiangnan has a humid climate and fertile land, which is suitable for developing productive forces.

The southern rulers took some measures to develop the economy.