Consequently they'd hook up a couple of horses to a chariot and you could pull two men in battle ~ although those same two men would be too big for the horses to ride, and would wear out quickly.
Later, through adroit use of animal husbandry (eat the small ones, breed the big ones) horses got big enough to ride.
During the early stages of horse culture guys on chariots rode back and forth from China to Central Europe on chariots ~ various improvements were invented all along the way. They have literally dug up some of the very first axle rigs ever manufactured ! This stuff is that new ~ it's not Ice Age work.
The Greeks, Romans, Persians, Egyptians and Chinese would have been astounded at the big Belgian horses developed for the carriage of armored knights! Those guys are about as big as the elephants in use in Hannibal's time.
Indo Europeans "received the horse" from others ~ but I think they put them to use faster and more effectively than any other group. Hence the successful spread of their language(s).
Yep, a Knight would get up on his “high horse” and ride over other cavalry. Those suckers were like Clydesdale's, but mean!