Imagine sitting on your hill in pre-biblical China, head full of dank.
The sun's gone down so you can't really space out on much anymore. You still have to wait a few thousand years for someone to invent the TV (lord knows your high-on ass is never gonna get around to it). And all the little noises coming out of nowhere are starting to freak you out.
The centuries pass. Herbal medication takes on a traditional role, passed down from generation to generation. Somewhere along the way someone on the next hill over invents gunpowder. You guys hang out one night, get bored, and decide to start seeing if you can do anything cool with the stuff.
Fireworks are born.