Why did the chinese silk trade die during the ming dynasty

1368: The Ming Dynasty began with a rebellion, which defeated the Mongol-led Yuan Dynasty (1271–1368).
1402–1424: Emperor Yongle ushered in a period of prosperity, including trade with Europeans. This continued until the late 1500s, when it was forbidden due to armed smugglers and Japanese pirates.
1420: The Ming capital was moved to Beijing after the Forbidden City was completed. Before that, the capital was Nanjing.
Traditional culture flourished during the Ming Dynasty. Three of the Four Great Classical Novels of Chinese Literature were written.
The Great Wall was more crucial than ever in protecting China from northern invasion during the Ming era.
1644: The dynasty ended when peasant rebellion from the south led to the Great Wall gates being opened to the Manchurians, who initiated the Qing Dynasty (1644–1912).

Southern secession is the event or issue that historians can gain insight from this excerpt.