Warning: Looong post
I definitely agree that grading civs based on versatility, and not specialization, is a flawed system. For instance, some players grade Brazil and Venice highly due to their ease of getting, respectively, cultural and diplomatic victories, but they don't downgrade them for their relative weakness at domination victories. However, I noticed that some people are quick to downgrade domination-oriented civs for not being good at the other victory types. I don't like this inherent bias against domination civs
Personally, I would move the Huns and Mongolia up to the highest tier. The biggest reason why they were relegated to the middle-range tiers on other tier lists was because they 'lacked versatility', and were considered to be good only at warfare. But if versatility (in the different victory types) is not considered, and the only thing that matters is how easy it is to win, then the Huns and especially Mongolia are much better at what they do than their fellow civs in the upper tier category. Especially on Pangaea maps. I play on Deity, standard size, standard speed, single-player.
The combination of Keshiks and Khans is just too good and completely negates the lack of usefulness of the attack bonus to city-states. I've noticed that people tend to devalue Keshiks by comparing their 16 ranged strength versus the camel archer's 21, but a Keshik should Always have 18.4 ranged strength (higher than a crossbow) due to the Khan's 5 movement. I have an easier time getting Mongolia deity domination wins than with Arabia (which, admittedly, is also easy but takes a longer time and is more likely to be circumstantially slowed down due to rough terrain or the Great Wall, or allowing units to heal after fighting in such difficult circumstances).
I open Honor, get the free Khan to scout, heal and help my early units kill barbs. Get a trade route to sponge off deity AI science, snab a CS worker, etc. Settle 1-2 more cities for horses. Get Military Tradition so that Keshiks can get Logistics with about 17 total shots against cities (25 total against units). And fill out the right side of Liberty, then finish Honor or whatever. Usually I fortify a cheap unit and road-connect the city for 2 extra happiness, and raze the unimportant ones. I don't really see the value in Tradition when I'm going to end the game before the growth bonus truly kicks in, and I'm trying to maintain unhappiness so that I can move onto the next enemy city without stopping.
1) The Keshik's 1 extra movement is HUGE. It's the difference between moving 3 rough terrain versus 2. It allows Keshiks to move onto rough terrain, shoot twice, and move back. It allows Keshiks to move onto Great Walled open terrain, shoot twice, and move back; or move onto Great Walled rough terrain, shoot once and move back. Camels can't do any of that. It allows Keshiks to travel 4(?) more tiles when using roads. I get plenty of damage with the 18.4 ranged strength and ability to shoot twice regardless of terrain. It takes 17 shots against cities to get Logistics with Honor, and unlike the Camel Archer, the Keshik has many more opportunities to double-shoot each turn regardless of terrain; not to mention that the Keshik will get Logistics much, much faster, which means range and march in no time (+25 HP healing every single turn with Khans; it's not necessary 95% of the time, but the fact that it's available is still impressive)
2) Mongolian horsemen's 1 extra movement is also VERY good at the point in the game when Keshiks are rampaging the earth. A regular 4-movement horseman cannot move 3 tiles of any kind in a Great Walled city so it (or another unit) NEEDS to take a hit in order to capture a city. But a Mongolian horseman can, allowing them to capture 0 HP cities from 3 non-rough tiles away in Great Walled territory. And it also comes into play when capturing a city that is surrounded by rough terrain, allowing the Mongolian horsemen to move 3 rough terrain to capture a city. Why is this good? Because it's convenient as heck, and allows for faster capturing of cities without the risk of your precious city-capturing unit (admit it, you only have around 2 horsemen in your entire Mongolia/Arabia army
) getting 2-shotted by a city and killed in 1 turn.
3) The attack-bonus to city-states is not COMPLETELY useless. It's extremely situational (i.e. when declaring war against deity Greece, he's bound to have an allied CS or two near your borders) then you'll have a quicker time getting rid of the invading CS fodder. Unfortunately, the expansion packs got rid of the CS-conquering quests, which was what the UA was good for originally. 0/5 is harsh. 0.5/5 would be okay
4) Khans are severely underrated. They allow for constant warfare and no need to slow down. They are excellent throughout the ENTIRE game for their combat boost, healing, and ability to get where they're needed much, much faster than regular great generals. Oh, and you'll get many more of Khans, due to all the exp and GG bonuses, compared to other civs. You can basically consider every single one of Mongolia's units, and not just Keshiks, to have +15% combat at all times due to the Khan's 5 movement. I get so annoyed when playing another civ and having to put up with 2-movement great generals that can't keep up with my units, after being spoiled by 5-movement Khans.
Comparisons: a regular GG can move 1 rough terrain per turn; Khans can move 3 tiles of rough terrain (not counting hilled-forests/jungles obviously); a regular GG can move 8 tiles on roads, Khans can move 20 per turn. Khans are the best citadel-makers in the game for obvious reasons.
Also, the healing is legitimately overpowered. Yes, I know that Keshiks rarely get hit and that Khans won't have to use their healing ability on them most of the time. But in situations where they DO need to heal, it is absolutely priceless and allows you to continue your conquering almost immediately. Healing 25 HP outside friendly territory is super-useful no matter, and the Khan's 5 movement to get into position to heal is what makes it Very Practical and efficient (not having to move/organize your wounded units around to get healed by a medic). After providing the bonus damage to the Keshiks at the beginning of a turn, the Khan(s) can easily move to where healing is needed thanks to their 5-movement; then move back to provide the combat boost in the beginning of the next turn and return to heal again. Khans are useful in every single era and in combination with any land military unit, not just Keshiks. Seriously underrated.
Anyway, Mongolia feels so much more fluid and nonstop when going for a domination victory than any other civ including Arabia:
-All (relevant) units have 5 movement points (18.4 strength keshiks to kill units and damage cities, khans to support and heal, horsemen to capture cities)
-Not hampered by terrain and Great Walled cities (compared to other civs).
-Constant motion, never stopping but for a moment thanks to the Khan's healing
Sorry for the ranting nature of my post and the repetition of several points. On the other tier lists threads I never bothered to say much because I acknowledge that Mongolia is limited in playing style and is one of the least 'versatile' civs in the game, but when it comes to just plain winning the game, I firmly believe that Mongolia is right up there with the god-tier civs.