Roster must definitely consist of mounted archer, mongolian archer, raider, light cavalry, lancers and not yet added support unit.
For techs: mounted archer upgrades, not yet added raider upgrade (unique to the building), light cav upgrades, at least one new tech boosting steppe units.
Some more units would need Steppe category added.
Maybe some completely new units needs to be made.
In civ 5, there is also keshik of mongolia that replaces knight
Military unit of the Mongols
The mangudai or mungadai were military units of the Mongol Empire. Source: wikipedia
Basically mongolian horsearchers are the nomadic raider archers while their upgrade, the mangudai are properly trained military archer units.
I remember suggesting many stats, but dont remember which topic, anyways considering the changes in aos, my old suggestion is already obsolete so we should make new stats