Persian cavalry before the cataphractarii

The Persians did not use cavalry to a great extent until Cyrus the Great  gave the Persian nobility both horses and the wealth to maintain them from the proceeds of his western conquests. He encouraged them to ride and it became a source of disgrace for a Persian noble to be seen walking.  Cyrus then recruited his cavalry from the nobles, creating a regiment of 15,000 men drawn from the Huvaka or “kinsmen.” These kinsmen adopted brightly-colored trousers and shorter tunics that were more suitable for riding from the Medes.  Cyrus adopted cavalry tactics from the Khorassan horsemen of northeastern Iran, parts of modern Afghanistan and the southern parts of Central Asia. He initially armed his cavalry with the standard weapons of the Persian infantrymen: bows, battle-axes, and oval shields. Later, they were re-equipped with short stabbing swords and throwing javelins instead. Long lances and spears made of wood or entirely of metal were used too.

In the mid-5th century Persian cavalrymen adopted the use of wicker and leather shields.  They were designed after those carried by the Saka, a group of nomadic Iranian peoples who historically inhabited the northern and eastern Eurasian Steppe and the Tarim Basin.

According to Herodotus, at the time of the Persian invasion of Greece, Persian cavalry, assembled from a variety of contingents within the empire, were protected only by various kinds of soft headgear and wore no substantial body armor. This is reflected both in the 3rd century BCE Cypriot statuette as well as the famous Alexander mosaic from the House of the Faun in Pompeii.  Cavalry officers may have worn more protective armor, however, as indicated at the battle of Plataea where Masistius, a Persian cavalry commander, is reported to have worn gold scale armor under his scarlet surcoat. 

"When his horse was hit by an arrow, he defended himself vigorously on foot and could not be brought down by body blows. At last, the Athenians who surrounded him guessed the secret and struck at his face." - The Persian Achaemenid Army, weaponsandwarfare.com

Detail from the Alexander Mosaic from the House of the Faun in Pompeii depicting Achaemenid Persian cavalry at the Battle of Issus, 1st century BCE-1st century CE at the National Archaeological Museum in Naples courtesy of Wikimedia Commons contributor Lucas.

Terracotta statuette of a horseman, 3rd century B.C.E. Cyprus, at the Metropolitan Museum of Art in New York.