Every time I think about it, it blows my mind that human beings domesticated and then rode the horse for thousands of years before figuring out that stirrups were a good idea.

Humanity had chariots and horse-drawn war engines and armies that conquered half a continent on horseback but nobody figured out that two leather loops makes you 10x better at riding and fighting from a mounted position. It's not like the technology wasn't there. Saddles had been a thing for thousands of years when someone thought "hey let's make the saddles just a little bit longer, you know, for the feet!"

That's like inventing the firearm and taking ten thousand years to invent the sling.