Hi all, I don't actually have time to join a mod team but if you're looking for direction or suggestions I guess I can help out.
Though be aware that history of the Mongols is a very difficult subject relying on archaelogical evidence for accuracy rather then written documents (100000000000 texts written about Mongols from our enemies, 1 text written by us). Also making a historical mod on the early periods of Mongol history would be quite difficult, thats when the least amount of history is known especially minor details. Nonetheless it would be interesting. Now I heard that the rise of khergits mod has moving villages - if that is true, we can change the graphics of the villages, utilising their code, and make it look like a nomadic tribe (don't make them move too much though).
I like the idea of uniting the tribes against a known enemy attempting to annex tribes one by one (as was history), so have as many important (historically as possible) Mongol and Turkic tribes, as well as the Tanguts. If we can implement the great wall it would be great

Classic! Dealing with Mongol tribes however is a difficult issue, tribes are all over the place and one tribe can have many subtribes and one subtribe can have a larger tribe with the same name etc. One note though, if you approach central asian tribal history with a mentality 'This is a Mongol tribe or this is a Turkic tribe', then you may risk arguing nonstop with facts thrown left right and center (Many Mongols and Turks have actually made this into a 'popular' hobby), as both ethnics have ended up 'sharing' certain tribes.
Here's what I propose for tribes based on historical importance and warring:
Merkits - north
Jadarad - central (Jamukha's tribe)
Kiyad - central (Temujin's tribe)
Tatar - east
Tayichuid - south east
Oirat - west
Kerait - central (Toghrul's tribe, known by Chinese as Wang Khan)
Naiman - west (We can use Kushluk as leader perhaps)
There are many important tribes such as the Uyghurs, Kyrgyz, foreign Khanates such as the Kara-Khitan as well but we can't include everyone.
Now we also have to set a timeframe on which period, since these tribes historically switched sides quite a bit. Or we can make it random. We also have to code renaming the united tribes as Mongols, and renaming character names would be good too, if it's possible. Khan means leader, Khagan means pretty much Khan of all Khans, but there will no Khagan during this period, so we'll stick to Khan. Let the player whichever tribe he choses be able to be appointed by the Kurultai as Chingghis Khaan

(If he manages to unite the tribes of course)
In terms of troop terms, during this period, it's light cavalry only, with Mongolian horses (much smaller then stallions, your feet is almost touching the ground) - if we can even mod that. Weapons? Bows, lances, axes, maces, and sabres. Troop battle alignments historically considered of 6 archers per 4 lances. So pretty much only 2 troop types (upgraded as they go along I guess). Women played a military role in defence of camps but not on the front lines, we can put them in camp defense. Note too every Mongol knew how to ride before they could walk, all men of able body trained, hunted and fought for their Khans, women were trained in martial skills to protect the families while the men rode to war. This is a nomadic culture in a harsh land, there were no 'civilians'.
So what you think? Can we do this?