Asap.. what generalization can you make about the shift in the center of population between 1840 and 1930? what change in the population could account for this shift? plz ; -;

The Song Dynasty. it was prosperous in many respects of the society. In agriculture, the productive technology was improved which promoted the output of food; in handicraft industry, the division of labor became more detailed which made the  handicrafts technology reach an advanced level; additionally, the development of the commodity economy exceeded the previous level. Particularly, the earliest paper currency appeared at that period.