Sorry, we don't allow throughout history questions. These tend to produce threads which are collections of trivia, not the in-depth discussions about a particular topic we're looking for. If you have a specific question about a historical event or period or person, please feel free to re-compose your question and submit it again. Alternatively, questions of this type can be directed to more appropriate subreddits, such as /r/history or /r/askhistory.
Opium was quite popular. It was a huge industry in India. The British Empire of the 1800s made vast sums of money by growing opium in India and then smuggling it into China... then using that money to buy Chinese tea (and other goods) for shipment to England where vast profits were again made. The profits were then used to buy more Indian opium to smuggle into China.... you get the idea.