"And there came with them an army that made the plains black like to ebony, and the sounds of their war trumpets made the heart to tremble."
— Ferdowsi, Shahnameh
Tarkhan are cavalry fielded by Mongol tribes and their erstwhile cousins, the Turks, but with a difference: while they may not be as cheap as Russia's Pomestia Lancers, they however have one fundamental feature: they are very tough riders. In fact, these mace-armed warriors are so hardened, that they cannot be considered light cavalry but rather as medium cavalry: they may have the same cost as any other light horse units, however, they have sufficient armour, attack and hitpoints to challenge even the mailed knights of Europe. Even so, they will crumple easily if faced with heavy infantry, so you should always be wary as to how you deploy them: Noble Knights should be avoided at all times, although it may be a bit of a relief to know that they have fairly steep reseach requirements.
Although long a title in Turkic society, the title of Tarkhans did not obtain any historical significance until the 14th century among the Central Asian Khanates (in Egypt, it was an honorific bestowed on military pensioners). Although sometimes civilians that had performed exceptional services (such as leading a khan's family to safety iat the cost of personal endangerment), the more common way for tarkhans to arise was through military distinction — in the army of Tamerlane, the Tarkhans were military officers in charge of contingents of armed men. In the face of weak rulers, the Tarkhans could eventually prevail, just as how in Rome the Praetorians eventually could usurp power in the Late Imperial period: the Tarkhans in India were descended from one such nobleman who seceded from his lord.
- Toughened medium cavalry unit capable of knocking out other light cavalry units, and swarming heavy cavalry.
- For the Horde! — Due to their toughened stance, Tarkhans are capable of countering other cavalry units, either through sheer numbers, or by their stats alone. Once you reach the later eras, the Tarkhan can give your army the edge it needs to keep fighting, especially since you cannot research Centralisation.
- Fight Knight — Knights are indeed very tough enemies, and so when using Tarkhans on the attack, you must build them in groups large enough to surround your opponents' cavalry. In a one-on-one battle, Tarkhans eventually lose out to the heavier Knights and Noble Knights, thus you must train as many Tarkans and upgrade them whereso needed.
- Bullseye — Because of their specialties, you must be careful of how you use your Tarkhans. True, Tarkans can kill many weaker unique units, such as the Muslim infantry and camelry, but against stauncher foes such as Italian elmetti or pikemen, the best action would be to avoid them where possible.
Tests showed that even with crappy infantry and Castle Age-grade horse archers, Tarkhan cavalry rampaged through Norse and German villages with impunity on deathmatch. A Military level requirement has been added to nerf it for balance.