 Shortly after his peace treaty with the Romans, Yazdegerd II moved towards the important Sasanian province of Armenia and defeated the Armenians, capturing nobles, priests, and troops; and sending them to the eastern Sasanian provinces to protect the borders from Hephthalite attacks.In the 440s, Yazdegerd II had a mudbrick defensive system constructed at Derbent to fend off incursions from the north.In 453, Yazdegerd II moved his court to Nishapur in Khorasan to face the threat from the Hephthalites and left his minister ("wuzurg framadar") Mihr Narseh in charge of the Sasanian Empire.