women trafficing and Government's Role

One of students asked me a question about child trafficking in China. She was wondering why Chinese preferred to traffic immigrant children rather than commoners. She had thought immigrants in China are like those in the US.

But this case reminds me of women trafficking in the Qing. Susan Mann mentions that "Under High Qing laws, Common females were banned from the slave market." But she also points out this principle did not carry out in the reality. First, Qing government permit the buying and selling of women with white contract (that is, without official supervision), it seemed clear that young girls whose backgrounds were never checked could be rented or perchased by the lot.