The Elamites established the first known Persian dynasty in the third millennium BC. Another Aryan people, the Medes (the ancestors of the Kurds of today), created a unified empire in the northwestern part of that region around 625 BC. Cyrus the Great, who issued what some consider the world's first declaration of human rights, overthrew the Medes and established the Achaemenid Empire, expanding Persian control and influence from Egypt to India -- making it one of the largest empires in history. His descendants, Darius and his son Xerxes, invaded Greece but were defeated and expelled from Europe in 479 BC.
In the next century, Alexander the Great conquered Persia and ended the Achaemenid dynasty. After about a hundred years of Alexander's Seleucid Empire, the Parthian and Sassanid dynasties reestablished Persian rule until the Arab invasion in the seventh century AD. The Persians, the Kurds, the Turks, and others then converted to Islam. (All Facts Considered, by Kee Malesky)