Horses were essentially used for pulling rather than for riding in early history. Stirrups were most likely introduced after 800 BC and changed the course of history.  This seemingly insignificant piece of riding equipment changed warfare dramatically. For once introduce, warriors could attack with swords or lances because the stirrups afforded them the balance required to use such weapons. In addition mounted riders now were able to flee attackers much more rapidly. Thus the military term strategic withdrawal came into use. Instead of  "run for your lives". The first stirrup were actually toe rings and were found in India about the 2nd century BC. Stirrups designed to accept the entire foot were recorded in China about the 4th century AD. This made mounting much more safe while carrying weapons. By the 8th century the use of stirrups had spread throughout  central Asia and Europe and by the 8th century had revolutionized warfare.

Today stirrups have been refined for particular uses. The English stirrup iron is referred to as a Fillis Iron and is weighted so that if a rider loses a stirrup, finding and gaining it's use again will be quicker. There are exercise irons used by exercise riders at racetracks. Jockey irons used by jockeys while racing horses. There are a number of safety irons such as the peacock iron or the foot free stirrups that will assist in freeing a riders foot  in case of an untimely fall.

Western stirrups are made of wood, plastic and aluminum. Some are covered with leather or rawhide. Some Aluminum stirrups are engraved and some have sterling silver plates added for overall appearance. So you can see that a simple device that is essential to the horse riding industry did play a big role in the history of mankind.