The history of the Achaemenid dynasty is mainly known thanks to Greek historians as Herodotus, Ctesias and Xenophon, tales of Old Testament books, and native Iranian sources. According to Herodotus, Achaemenids were a clan from the tribe of the Pasargadae and probably settled surrounding the sites of Pasargadae. They possibly ruled over other Persian tribes in the 9th century B.C.