You can’t necessarily make that comparison since you’re dealing with different groups of people. This study indicates the Yamnaya- a pastoralist people of the Pontic-Caspian steppe- were riding horses several hundred years before the great pyramid was built in Egypt. It’s also important to note that horse domestication =/= horse riding. Even this article notes evidence of horse domestication that predates this. Meat, milk, pack animals, chariots, these things all likely predate horse riding given that wild horses didn’t have backs strong enough for it. Horse riding likely would’ve come along after generations of domestic horse breeding for those purposes.