The Han Dynasty 's military expansion widened its commercial ties in addition acquiring large amounts of new territories .
Political upheaval in the north , such as Wang Mang 's usurpation , had caused Han migrants to resettle in the south .
The Han   's military expansion widened Han 's commercial ties in addition acquiring large amounts of new territories .
Political upheaval in the north , such as Wang Mang 's usurpation , had caused Han migrants to resettle in the south .