The first use of horses in warfare occurred over 5000 years ago. The earliest evidence of horses ridden in warfare dates from Eurasia between 4000 and 3000 BC. A Sumerian illustration of warfare from 2500 BC depicts some type of equine pulling wagons. The effectiveness of horses in battle was also revolutionised by improvements in technology, including the invention of the saddle, the stirrup, and later, the horse collar.
Many different types and sizes of horses were used in war, depending on the form of warfare. Horses were well suited to the warfare tactics of the nomadic cultures from the steppes of Central Asia. Several East Asian cultures made extensive use of cavalry and chariots. Muslim warriors relied upon light cavalry in their campaigns throughout North Africa, Asia, and Europe. Europeans used several types of war horses in the Middle Ages, and the best-known heavy cavalry warrior of the period was the armoured knight. With the decline of the knight and rise of gunpowder in warfare, light cavalry again rose to prominence. In the Americas, the use of horses and development of mounted warfare tactics were learned by several tribes of indigenous people.
Horse cavalry began to be phased out after World War I in favour of tank warfare, though a few horse cavalry units were still used into World War II. By the end of World War II, horses were seldom seen in battle, but were still used extensively for the transport of troops and supplies. Today, formal horse cavalry units have almost disappeared, although horses are still seen in use by organised armed fighters in Third World countries. Many nations still maintain small units of mounted riders for patrol and reconnaissance, and military horse units are also used for ceremonial and educational purposes.