Cambyses I was king of Persis (c.600-559) and the father of Cyrus II the Great, founder of the Persian Empire. Cambyses inherited the throne of western Persis (or Anshan) from his father Cyrus I. Eastern Persis was then held by the family of his uncle Ariaramnes, brother of Cyrus I. For the last two generations Persis had apparently been free of Median control, largely due to the 'Scythian interregnum', a period where Scythian nomads from the east briefly overthrew the Median rulers. According to Herodotus the Scythians were overthrown by Cyaxares of Media (625-585 BC), who got their leaders drunk at a party and then killed them. Cyaxares then restored Median control over Persis, and appointed Cambyses as ruler of both halves of Persis.
Cyaxares was succeeded by his son Astyages (r.585-550). At some point after Astyages came to the throne he married his daughter Mandana to Cambyses and in around 575 BC they had a son, the future Cyrus II the Great. As might be expected plenty of legends surround Cyrus's childhood. According to the most famous, Astyages chose to marry his daughter to Cambyses in response to a dream. After the birth of Cyrus he had another dream, this time suggesting that the young prince would overthrow him. Astyages sent a general to assassinate the young Cyrus, but instead he chose to hide him away. Cyrus was raised by a shepherd, but his real identity was later revealed and he was allowed to succeed his father Cambyses as king of western Persis and presumably overlord of eastern Persis.