Qajar is the one Modern civilization built to reward staying under your Settlement Limit rather than pushing past it — a genuinely different incentive structure that favors a smaller, more efficient empire.
"Kayānī Crown" grants increased Influence toward supporting Diplomatic Actions initiated by other leaders — genuinely rewarding other civilizations for including you in their diplomacy. Its Civics add further bonuses tied specifically to staying below your Settlement Limit, including Combat Strength and capital yield bonuses that scale with how much headroom you have left.
The Sardār is a unique Commander with increased Movement that can also raze extra Districts per turn in Settlements it occupies. The Gholām is a unique Cavalry unit that gets increased Combat Strength and HP healing specifically within a Sardār's command radius, meaning it functions best paired with that Commander rather than operating alone.
The Takyeh (Happiness, with Influence adjacency from Culture Buildings) and Ghahve Khaneh (Food, with Happiness adjacency from Gold Buildings) are unique buildings, combining into the Bāq Unique Quarter, which boosts Influence and Culture during Celebrations. The associated Wonder, Eram Garden, increases the Specialist Limit in its city and must be built on Desert.