Persia’s had a long life as civilizations go.  Thousands of years.  They’ve seen lots of nations, lots of faiths, and lots of people flow through them.  And while others have conquered their land, nobody ever really conquered the people.  They waited, and when their occupiers revealed their idiocy, they took over again with their Persian Revolutions.  Every time.  Governments and names may come and go, but Persia is eternal in their eyes.