1940s? >>8621607

"Starting in in the mid-1700s, the British began trading opium grown in India in exchange for silver from Chinese merchants. Opium — an addictive drug that today is refined into heroin — was illegal in England, but was used in Chinese traditional medicine.

However, recreational use was illegal and not widespread. That changed as the British began shipping in tons of the drug using a combination of commercial loopholes and outright smuggling to get around the ban"

"In 1839, England went to war with China because it was upset that Chinese officials had shut down its drug trafficking racket and confiscated its dope."

https://nationalinterest.org/blog/the-buzz/the-opium-wars-the-bloody-conflicts-destroyed-imperial-china-17212