It is a prerequisite of chivalry.
Horses are believed to have been first domesticated in the great plains of northern Asia. Mounted horsemen from this region migrated into the more civilized parts of Europe and Asia, often driving out or enslaving the inhabitants. Where the horse could be raised, Horseback Riding was extremely useful as a source of power and means of transportation. It proved especially valuable in battle, making the rider much more imposing and mobile. Mounted warriors were part of most armies until their role as scouts and Cavalry was superseded by vehicles and aircraft.