The most significant fact of early and mid-Qing social history was population growth. The population doubled during the 18th century. People in this period were also remarkably on the move. There is evidence suggesting that the empire's rapidly expanding population was geographically mobile on a scale, which, in term of its volume and its protracted and routinized nature, was unprecedented in Chinese history. Indeed, the Qing government did far more to encourage mobility than to discourage it. Migration took several different forms, though might be divided in two varieties: permanent migration for resettlement, and relocation conceived by the party (in theory at least) as a temporary sojourn. Parties to the latter would include the empire's increasingly large and mobile manual workforce, as well as its densely overlapping internal diaspora of local-origin-based merchant groups. It would also included the patterned movement of Qing subjects overseas, largely to Southeastern Asia, in search of trade and other economic opportunities.