In Age of Empires 4, "The Battle of Zhongdu" mission focuses on the Mongol Empire's siege of the Jin Dynasty's capital, Zhongdu (modern-day Beijing). Players lead the Mongol forces under Genghis Khan in a strategic campaign to conquer the heavily fortified city. The mission involves deploying siege weapons, managing resources, and overcoming the strong defenses of the Jin Dynasty to achieve victory and expand the Mongol Empire's territory.