 Ardashir, before becoming king of the Sasanian Empire, was governor-king of Nodardashiragan from 344 to 376.It is believed that during his tenure he took part in the defense of the Sasanian Empire with Shapur when it was invaded by the Roman Emperor Julian ().In 379, Shapur II designated Ardashir as his successor, and made him vow to abdicate when Shapur's son, Shapur III reached adulthood.