Hydarnes remained an influential man during the reign of Darius. From tablets found at Persepolis, it is known that he was satrap of Media in 499 BC. The influence of Hydarnes also secured the appointment of his sons as satraps. Herodotus states that Hydarnes’ son Sisamnes was the satrap of Aria and that the younger Hydarnes was "in command of the whole Asian seaboard". During the Second Persian invasion of Greece in 480 BC, the younger Hydarnes was given command of the "Immortals"; while Sisamnes was given command of a levy of Arian troops.