The history of humans is all about horses. The only cultural developments of note between the agricultural revolution and the industrial revolution are the rise of cities and the domestication of horses. Navigation is also significant, but I suspect pre-dates the agricultural revolution. I think western historians have a blind spot in this area due to their own slow development, and subsequent disregard of others’ in the South Pacific and elsewhere. But nothing compares to horses. The history of the domestication of horses parallels most of the history of world civilization and is intrinsic to it. When horses were domesticated enough to pull two-man chariots, warfare was revolutionized. The advanced cultures in the Middle East were quick enough to recognize the change and adapt. But for the primordial culture of Europe and the decadent Indus Valley culture of India, it was too late. Indo-European speakers took over. When horses became domesticated enough, and people became skilled and brave enough, to ride bareback a thousand years later, a new era emerged again, that of the steppe raiders, almost unstoppable in their ability to raid cities and then retreat to safety. Only iron armor was able to stop their onslaught. Fast-forward another thousand years and throw in iron stirrups, and they were unstoppable. Thus began the true age of cavalry and horse-powered transportation, refined and polished until finally made obsolete only by the development of wheeled vehicles powered by internal combustion engines.