In the 1800s what item did the europeans unleash in china that made for lucrative trade

Opium. European traders and chinese merchants had first met at the markets of Bantam. the Europeans bought tea, silk and porcelain and the Chinese wanted silver in return. And when the tea had became a popular drink in England, the Europeans don’t want to pay too much silver for it so they involved in a triangular trade by smuggling opium which is a valued medicine in China.