In the era when there were no saddles or stirrups, people needed to ride on the bare back of the horse, relying only on grabbing the reins or mane and clenching their legs tightly around the horse's belly to prevent falling off when the horse dashed.
But this method was very unreliable. First, it was easy to become fatigued from long periods of horseback riding. At the same time, it was difficult to effectively use bows and arrows on the moving horse's back. In close combat, the riders could not wield swords and spears as they wished. A strike missing its target, or the collision of weapons, could cause the rider to slip off the horse at any moment.
Therefore, cavalry training was extremely difficult, hard to scale up, and not as effective as in future eras.
Only after the saddle was invented could the cavalry develop on a large scale and significantly improve its combat effectiveness.
