Speaking Indo-European like the Medes, they had entered Iran at the same time as them at the end of the second millennium.
They settled in the 9th century in the country of Parsua, south and south-west of Lake Urmiah, then moved south-east to occupy the mountains of Fars. The Persians, like the Medes, were divided into tribes:the Pasargadae, the Maraphians, the Maspians, the Panthalians, the Deronsians, the Germanians, all farmers. It was joined by four nomadic tribes:the Daens, the Mardes, the Dropiques and the Sagartiens. The Pasargadae are the most important and the Hakhâmanich, a clan of these, of which the Greeks made the eponymous king Achaemenes.
They extended over the entire Iranian plateau where they founded an autonomous kingdom under the leadership of the first historical king, Achaemenes.
Towards the end of the 7th century, they appear in History thanks to Herodotus. They are then divided into two kingdoms governed by the descendants of Teispes, son of Achéménès. Over Persia proper, between Isfahan and Shiraz, reigned the family of Ariaramnes, eldest son of Teispes, while, further west, the country of Anshan was ruled by the family of Cyrus I, brother of Ariaramnes. . These two kingdoms were vassals of the Medes. For a generation or two, the house of Ariaramnes had dominated that of Cyrus I, but the latter's son, Cambyses I, reversed the balance of power by marrying the daughter of Astyages, king of Media, his overlord.
The Persians introduced the use of the horse, new deities and a religion that would long remain marked by the influence of Median dualism.