persia only got conquered like a handful of times throughout its thousands of years of history
>by alexander, a man who took over almost the entire civilized world at his time, and went down in history as the greatest conqueror who ever lived
>by the islamic horde that ravaged half the planet from morocco/spain in the west all the way to india in the east
>by the turkic/mongolian steppe nomads whose rampage across eurasia is estimated to have wiped out almost a quarter of the entire worlds population at the time
>by the anglos and soviets during ww2 (not really a lasting conquest, after the war they just left and handed the country back to the younger pahlavi)
notably, alexanders conquest was the only time another civilized empire managed to conquer persia, a feat neither the romans, the byzantines, the ottomans, or the russians managed to repeat