Evidence from archaeological digs suggest that horses were domesticated about 6000 years ago as a food source. How and where this first happened is something of a great mystery and is only now being understood to greater degrees.
Wild horses roaming free in the land were caught. Round pens were built to keep the wild horses inside. The mares (mother horse) were milked and the milk was kept in pottery vessels. It was fermented so it would keep longer as there was no way of keeping it cold. The fermented horse milk was called “koumiss”.
Koumiss is still consumed in some countries today.
Today, we may still milk the mare but we do not drink it. Sometimes the milk will be frozen and stored just in case a foal loses its mother and then the orphan foal will have some milk available.
We are not sure just who was the first brave person to try to ride a horse, but it may have been during this time. It is possible that ropes were used for the first riders to control the horses, and these would not survive as metal does, so all traces may be lost.