After the Tang Dynasty, the southward shift of China’s economic center of gravity became evident with the reign of the Wan Li Emperor, in the East Sea, the Yellow Sea, and the South Sea, Chinese ships and goods traveling between Fu Jian and Manila, contributed to early globalization. Nan Yang’s merchants and their families initiated the first wave of emigration. After the Second Opium War and the signing of the Treaty of Bei Jing , the Treaty of Tian Jin , the mass Chinese laborers became an unavoidable diplomatic and legal issue for the Forbidden City. In 1873, Chen Lanbin and his delegation began investigating the conditions of Chinese laborers in Cuba, Treaty on Chinese Laborers in Cuba was signed, this marked the first substantive action taken by Qing to safeguard the rights of emigrant workers. It also became an important component of the Zong Li Ya Men’s role in near-modern Chinese diplomatic history.
Yang Yang (Tue,) studied this question.