Peroz I killed in battle with the Hephthalites

Peroz had won the throne in 459 after a struggle with his brother Hormizd III — possibly with Hephthalite help, though the sources disagree — and around 466–467 he drove the Kidarites out of Bactria. His most dangerous enemy, however, proved to be the Hephthalites. He was twice defeated and captured by them; the dates of these wars are uncertain, between the late 460s and the early 480s. The first time he was released for a large ransom in gold obtained from the emperor Zeno; the second time he had to promise thirty mule-loads of silver coins and leave his son Kavad with the Hephthalites as a hostage.

In 484, once Kavad had been freed, Peroz raised a great army, advanced from Herat to Balkh and rejected the envoys of the Hephthalite king Khushnavaz (Akhshunwar). The Persians were ambushed — probably near Balkh; the exact site is uncertain (some works place the battle near Herat). According to Procopius, the Hephthalites had dug a deep, wide trench and hidden it under reeds and earth, and the Persian cavalry charged into it; modern scholars doubt parts of his account. Peroz was killed and his body was never found; four of his sons or brothers died with him (seven sons, according to Sebeos), and his daughter and his treasure fell into the enemy’s hands.

The nobleman Sukhra raised Peroz’s brother Balash to the throne. For two years the Hephthalites plundered the Sasanian lands, and the chief cities of Khorasan — Nishapur, Herat and Merv — passed under their rule; Iran paid them tribute for decades — until 496 by one account, until the mid-6th century by others. The weakened government also made peace in Armenia: in 484 Balash concluded the Treaty of Nvarsak with the rebel Vahan Mamikonian, guaranteeing the Armenians freedom of worship.