Game Info
The Mongolian unique ranged mounted unit. Replaces the Knight. Requires 
Horses Horses.
- Common traits:
- Can move after attacking
- Unable to melee attack
- No defensive terrain bonuses
- Special traits:
- No penalty when attacking cities
- Great Generals I promotion
- Quick study: Gains 50% more XP from battles
- Extra movement +1
Strategy
Using Keshiks
The Keshik possesses a strong ranged attack and an increased movement rate (5 points total), allowing it to perform hit-and-run attacks remarkably effectively. Although its attack strength is a bit weaker than that of both the standard Knight and the Arabian Camel Archer, it has other advantages: it acquires more experience than the other units, and contributes double the amount of points towards earning Khans. Also, Keshiks do not receive a penalty when attacking cities.
These mounted warriors single-handedly afford Genghis Khan and the Mongolians control of the open plains, decimating enemy forces from afar and quickly advancing in levels and becoming more and more dangerous with each passing skirmish. An army of Keshiks is very difficult for all but the most skillful and well-prepared opponents to repel.
Against Keshiks
Stronger and faster than a Crossbowman, about the only archery unit that can try to hold its own against a lot of Keshiks is the English Longbowman, with its longer range. It has a range of 3, as opposed to the Crossbowman's range of 2. If you are playing as England, you might try using large numbers of Longbowmen to defend against the Keshiks.
Chu-Ko-Nu may also provide a good defense against them if you are playing as China. Although weaker than Keshiks, Crossbowmen, or Longbowmen, their ability to attack twice more than makes up for this weakness. Position them all around your territory to create a defensive network that will rapidly wear down attacking Keshiks. Just beware of the Keshiks' movement, as they can perform hit-and-run tactics that may seriously hamper your Chu-Ko-Nu.
Another strategy is to use your own mounted units to rush the Keshiks before they can use their ranged attack. Keshiks are weaker than regular Knights in melee combat, but they are also faster and can retaliate against your Knights without taking damage themselves, so you will need to overwhelm them in as few turns as possible to avoid being worn down. Arabia's Camel Archers also have a ranged attack, so you can use the Keshiks' own tactics against them if you can catch them within attack range.
Using Pikemen against Keshiks won't work very well, because Keshiks will just stand away from your Pikemen and kill them one by one. Additionally, Pikemen don't get their 50% bonus against mounted units when fighting a Keshik because the game logic considers the Keshik a "ranged" rather than "mounted" unit (arguably a bug). Longswordsmen are too slow to attack Keshiks very well, despite their strength.
As with almost all units, Keshiks are severely damaged by powerful siege units (especially Trebuchets and Cannons), so always make sure that there is a siege unit in the city.
Historical Info
In the 13th century the Mongols came boiling out of Central Asia, conquering most of Asia, Eastern Europe and a large portion of the Middle East by the end of the century. The Mongols' primary weapon was their incomparable horse archers, the Keshiks. The Mongols were nomadic tribesmen, and their children were almost literally "raised in the saddle." Riding on their small but hearty steppe ponies, the lightly-armed and armored Mongols could cover an astonishing amount of territory in a day, far outpacing any infantry or even the heavier European cavalry.
In battle the Mongol Keshiks would shoot from horseback with deadly accuracy, disrupting and demoralizing the enemy formations. Once the enemy was suitably weakened, the Mongol heavy cavalry units would charge into the wavering foe to deliver the coup de grace. When facing armored European knights the Mongols would simply shoot their horses, then ignore or destroy the unhorsed men as they wished.