Under the Qing, foreign merchants could trade with China only through the Thirteen Hongs.
Tips
mistakes
行 is read háng here, "trading house" as in 银行, not xíng. The number of houses was not always thirteen.
history
From 1757 to 1842 Guangzhou was the only port open to Western traders, and every deal went through these licensed Chinese merchants, some of whom became among the richest men in the world. Today the area is a busy clothing wholesale market.