'The Afnan in China' was the main contact for opium traders.

It is noted in his biography in Fasaʾi, Farsnamih Nasiri, vol. 2, p. 45, that, due to economic depression in Fars and family bankruptcy, Haji Mirza Muhammad-ʿAli went to China for 10 years. There, he became the main contact for the opium trade of the merchants of Isfahan, Yazd, and Fars. In the Writings of Bahaʾuʾllah, he is referred to as “the Afnan in China.” See Bahaʾuʾllah’s Tablet in Fayzi, Khandan Afnan, p. 83.

Source : The Genesis of the Bábí-Baháʾí Faiths in Shíráz and Fárs, By Mirza Habibuʾllah Afnan, Translated and Annotated by Ahang Rabbani, Page 319

https://bahai-library.com/pdf/a/afnan_rabbani_genesis_faiths.pdf