The ruling dynasty of the Persians settled in Fars in southwestern Iran (possibly the Parsumash of the later Assyrian records) traced its ancestry back to an eponymous ancestor, Haxamanish, or Achaemenes. There is no historical evidence of such a king's existence. Traditionally, three rulers fall between Achaemenes and Cyrus II: Teispes, Cyrus I, and Cambyses I. Teispes, freed of Median domination during the so-called Scythian interregnum, is thought to have expanded his kingdom and to have divided it on his death between his two sons, Cyrus I and Ariaramnes. Cyrus I may have been the king of Persia who appears in the records of Ashurbanipal swearing allegiance to Assyria after the devastation of Elam in the campaigns of 642-639 BC, though there are chronological problems involved with this equation. When Median control over the Persians was supposedly reasserted under Cyaxares, Cambyses I is thought to have been given a reunited Persia to administer as a Median vassal. His son, Cyrus II, married the daughter of Astyages and in 559 BC inherited his father's position within the Median confederation. Cyrus II certainly warranted his later title, Cyrus the Great. He must have been a remarkable personality, and certainly he was a remarkable king. He united under his authority several Persian and Iranian groups who apparently had not been under his father's control. He then initiated diplomatic exchanges with Nabonidus of Babylon (556-539 BC), which justifiably worried Astyages. Eventually, he openly rebelled against the Medes, who were beaten in battle when considerable numbers of Median troops deserted to the Persian standard. Thus, in 550 BC, the Median Empire became the first Persian Empire, and the Achaemenid kings appeared on the international scene with a suddenness that must have frightened many.