Age of Empires IV's Delhi Sultanate civilisation is another one of the RTS game's more difficult factions, rated a three out of three stars in-game. They are a defensive and research focused civilisation, although they don't have notably unique mechanics like the Mongols or the Abbasid Dynasty - barring one key exception, they largely play like any other faction.
This exception is themed around technology - the Delhi Sultanate gets access to the Scholar unit from the Dark Age via the Mosque, which is also available from the start of a match. In addition, this civ gets to research every technology in the game for free - but each tech takes time to complete. This can be sped up by scholars, much like how the Chinese administrator unit can give boosts to economic yields.
Scholars only apply their research bonus if they are garrisoning a building, and techs can improve their utility by letting them garrison buildings they wouldn't normally be able to, like the barracks. Other buildings built within the influence range of a Mosque can also get faster research speeds, depending on how many scholars are garrisoned in the Mosque itself.
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