This is a question that comes up here fairly regularly, and the answer is that there is considerable dispute nowadays as to whether the Black Death originated in, or ever actually reached, China; an alternate origin in a "plague reservoir" close to the Caspian Sea is now considered likely by at least a significant proportion of historians of the pandemic.

These two threads, the first led by me and the second by u/y_sengaku, give more details of the debate:

Why can't I find very much information about the 14th Century black death in Asia?

Why didn’t Asia and Africa experience what Europe did during th Black Death?