I’ve already got some ideas about the UU of potential Asian civs, let me share them with you.
Khitans: earlier some people proposed their UU should be the crossbow cavalry, but such a unit isn’t historical at all. I’ve searched through historical records and found a more suitable UU, the Pishi Guard. The Pishi Guards started off as the guardsmen around the palace of the Khitan emperors, but later became a fully fledged army. And historically speaking, Khitans liked to use blunt weapons such as maces. I’ve envisioned the non-elite version of the Pishi Guard as a heavy infantry armed with a mace and a shield, and the elite version would be similarly armed except that it would be mounted on a horse and thus becomes a cavalry unit. Such a infantry-cavalry distinction between the non-elite and elite versions would make it rather special unlike any unit so far in the game, and would also fit with the historical Khitan Liao empire as an empire that straddled between agricultural and nomadic zones. And the special ability of the Pishi Guard (both the non-elite and elite versions would have this) is the stunning effect, able to stun/immobilize the enemy unit for 1.5 seconds with its first strike, and after that it would take some time to recharge until it could perform another stunning effect.
Jurchens: their UU would be the Iron Flail, a heavy cavalry that uses a flail to attack the enemy. It would have a range of 2 and its attack effect would be similar to the Scorpion.
Tanguts: their UU would be the Camel Slinger, a camel rider armed with a slingshot, and has a bonus attack against infantry units. Basically an Incan slinger mounted on a camel.
Tibetans: their Castle UU would be the Tibetan Mastiff, a war dog that has a bonus attack against infantry and villagers. It should probably be in an armor class of its own. They have another UU or rather a unique upgrade, and that is the Imperial Steppe Lancer, which is upgraded from the Elite Steppe Lancer. And its stats would be similar to a Paladin. To compensate, this civ wouldn’t have access to Knights, they have to rely entirely on their Hussars and Steppe Lancers.
Dians (Nanzhao): their Castle UU would be the Luojuzi, a fast-footed skirmisher (speed 1.2) that does not have a bonus attack against archers but instead has a bonus against cavalry and camels. They have a secondary UU at their Barracks called the Raeu Tribesman, which is a dual-purpose unit that can transform between an infantry mode and a gatherer mode. In the gatherer mode it can gather all resources just like a villager, but unlike the villager it would drop off the resources at the Barracks.
Chams: their UU would be the Haluwbilau Raider, an infantry unit that has a bonus attack against all civilian units (villagers, trade carts, trade cogs, and fishing ships). It’s both a ranged and melee unit. When the enemy is at a range greater than 2 it would throw spears at him (max range is 4), and the spears would deal melee damage instead of pierce damage. And when the enemy is less than 2 tiles away it would automatically switch to melee mode.
Siamese: their UU would be the Elephant Gunner, a conquistador like unit that rides an elephant instead of a horse. And it would deal bonus damage against siege weapons and defensive structures.
Mons, Javanese, and Visayans I haven’t thought about them. Any ideas about what their UUs might be?
Moluccans: their Castle UU would be the Alifuru Warrior, a very fast infantry unit (speed 1.3) with a large LOS (10 LOS), armed with only a shield and a saber, and with naked upper body just like the Karambits. This civ has the worst stable out of all Old World civs, with only the Scout Cavalry available (cannot upgrade to Light Cavalry), hence this UU serves as a replacement for their Knights and Light Cavalry. Its special ability is that it has a poisonous attack, with affected enemy unit continuing to lose HP for 5 seconds after a battle with the Alifuru Warrior is over. Although it’s not known if the Alifuru people would smear poison on their sabers, applying poison to arrowheads, javelins, spears, and sabers were a quite common practice among the tribal peoples of South China and SE Asia back in the days, so it’s not an over-exaggeration to depict them as such. Their Dock UU is the Cora Cora, an elongated warship with both sails and oars. It fires bullets just like a hand-cannoneer, and has a bonus damage against Fire Ship and Demo Ship. Its a dual-purpose ship, can be used to trade with allies as well, though with a lower gold-carrying capacity than trade cogs.