He is first mentioned some time in the 580s, when the Byzantine emperor Maurice (r. 582–602) requested the Armenian nobles to raise cavalry for service in his wars against the Avars.
[1] Smbat returned from exile some time after, and entered the service of the Sasanian shah Khosrow II, who in 595 appointed him marzban (military governor) of Hyrcania (the southern coastlands of the Caspian Sea).
[1][2] Smbat served in this post until 602, but was initially employed in suppressing the rebellion of Vistahm in Khorasan, before being recalled to reside at the royal court in Ctesiphon.
607 ("the eighteenth year of Khosrow's reign") he was sent back to Armenia with extensive powers as "Commander of the army of the lords of houses".
His tenure in Armenia was short but productive: as N. Garsoian writes, "Smbat’s extraordinary powers allowed him to reaffirm the authority of the Persian crown in Persarmenia, to restore the prestige of the weakened Armenian Church by summoning a council that elected a new katholikos, Abraham I, after a vacancy of three years, and to rebuild the cathedral of the Armenian administrative capital of Duin, overriding the objections of the local Persian authorities".