Mongolia

Mongolia is one of the most open maps in the game, with very few trees and wide expanses of flat land. Walling is nearly impossible, and any civ that depends on chokepoints or forests struggles immediately. Cavalry archer civs absolutely dominate: Mongols, Magyars, Tatars, Cumans, and Huns are S-tier here. The lack of wood also penalises archer-heavy civs that need lumber camps. Expect fast-paced raids, deep flanks, and very few drawn-out sieges.