I have written about the Mongol civ’s problem here:
This civ is utterly done wrong in so many ways.
At least, the 1st version of the civ was the most decent one, since then, they nerfed everything including its heavy cavalry into light lol. now they are one of the top horrible civs. They arent even a cav civ at all.
It is played against its civ strength “CAVALRY”. It has good infantry and tower rush LOL