The Cataphract is the upgrade of the Heavy Cavalry in Age of Empires. It is the strongest hand cavalry in the game besides hero units. To upgrade the Heavy Cavalry to a Cataphract, 1,600 food and 600 gold is required after Metallurgy is researched. Only a certain number of civilizations have the ability to train this unit. Cataphract deals +5 damage bonus against all melee infantry units except for Academy units.
While a somewhat handy unit just by itself, the cost of the upgrade is so ridiculously high that many players find it pointless to research, as it generally does not pay off. In Death Matches, Cataphracts are considered to be a good way for non-chariot civilizations to take on Catapults.
All East Asian civilizations have access to the Cataphract.
This in-game availability is historically accurate for the Chinese (chariots drawn by armoured horses were mentioned in Shijing and heavy cavalry were deployed during the Han dynasty) and Koreans (4th-century Goguryeo murals featured cataphracts) yet historically inaccurate for Japanese, as haniwa statues of only unarmored horses, not armored horses, were found. Japanese horse-armours weren't attested until the Edo period.
The Assyrians, Macedonians and Persians are the the only Middle Eastern, Roman and Central Asian civilizations that have access to them, respectively, and none of the Mediterranean ones have access to them.
The cataphract was an improvement on ancient heavy cavalry represented by Alexander the Great’s Companions. The Companions wore only helmets, greaves, and cuirass (breastplate). Cataphracts wore chain mail that covered more of the body and often armored their horses partially also. This gave greater protection against arrows and hand-to-hand weapons. Cataphracts were very expensive to equip, however, and appeared in the armies of only the most warlike and wealthy cultures.