The Mongol civilisation represents the greatest extent of Age of Empires IV's civilisation asymmetry. They are the horse lords from the steppes, nomads who managed to conquer and forge one of the biggest empires in history under Genghis Khan and his descendants. As such, they play very different to pretty much ever other civilisation, and are not for beginners.
For starters, they don't need to build houses - the Mongols start with the maximum population size. They get early access to both horsemen and lancers, and all of their buildings can pack up and relocate somewhere new. You don't want to be sitting passive with this civ - moving around and exploiting the terrain is key, but the Mongols' affinity for stone will focus your attention around the major sources of this resource on the map.
The Mongols are rated three out of three starts on the in-game difficulty rating. One of the few things that does play according to the same rules as everyone else is how they age up. You'll still need to build the landmarks as normal to progress through the ages.
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