A son of Yazdegerd II (r. 438–457), he disputed the rule of his elder brother and incumbent king Hormizd III (r. 457–459), eventually seizing the throne after a two-year struggle.

Early in his reign, he successfully quelled a rebellion in Caucasian Albania in the west, and put an end to the Kidarites in the east, briefly expanding Sasanian rule into Tokharistan, where he issued gold coins with his likeness at Balkh.

Before Peroz could quell the unrest there, he was defeated and killed in his third war with the Hephthalites in 484, who seized the main Sasanian cities of the eastern region of Khorasan−Nishapur, Herat and Marw.

Albeit a devout Zoroastrian, Peroz supported the newly established Christian sect of Nestorianism, and just before his death, it was declared the official doctrine of the Iranian church.

The empire reached its lowest ebb; the shahanshah was now a client of the Hephthalites and was compelled to pay tribute, while the nobility and clergy exerted great influence and authority over the nation, being able to act as king-makers.

[1] When Peroz's father Yazdegerd II (r. 438–457) died in 457, he had reportedly not designed a successor and instead—according to the medieval historian al-Tha'alibi—entrusted the task to the elite and the leading marzbans (margraves).

[5] Civil war soon followed; Yazdegerd II's eldest son Hormizd III declared himself king at the city of Ray in northern Iran, while Peroz fled to the northeastern part of the empire and began raising an army in order to claim the throne for himself.

[8][11] The modern historians Parvaneh Pourshariati, Shapur Shahbazi and Michael Bonner prefer the Armenian version, with the latter suggesting that the Persian account may yield some authenticity, with Peroz enlisting Hephthalite aid through the Mihranids.

[8][10][a] During the dynastic struggle between Peroz and Hormizd III, the Arsacid king of Caucasian Albania, Vache II (r. 440–462), took advantage of the tumultuous situation and declared independence.

Vache II abdicated in 462,[14] leaving Albania kingless until 485, when Vachagan III (r. 485–510) was installed on the throne by Peroz's brother and successor Balash (r. 484–488).

[20][25] Tensions continued to increase until the accession of the Byzantine emperor Zeno (r. 474–491) in 474, who resumed payment to Iran and also ransomed Peroz from captivity by the Hephthalites.

[27][28] Since the reign of Shapur II (r. 309–379), Iran had to deal with nomadic invaders in the east known as "Iranian Huns" and made up of Hephthalites, Kidarites, Chionites and Alkhans.

[39] After some time Kunkhas found about Peroz's deception, and in turn attempted to trick him, by requesting him to send military experts to strengthen his army.

But rumors of a caravan delivering tribute from the Iranian court to the Huns spread across the Iran and the Mediterranean worlds, as far as Sidonius Apollinaris in Gaul.

[36][56] Peroz imposed a poll tax on his subjects to raise the ten mule packs of silver, and secured the release of Kavad before he mounted his third campaign.

In Armenia, Yazdegerd II's policy of integrating the Christian nobility into the bureaucracy by forcing them to convert to Zoroastrianism had resulted in a large-scale rebellion in 451, led by the Armenian military leader Vardan Mamikonian.

[63] Espousing his pro-Iranian position, he attempted to force his family to convert to Zoroastrianism, including his first wife Shushanik (a daughter of Vardan), whom he eventually killed, which made her a martyr.

[74] Shapur Mihran restored Sasanian rule in Armenia, but was summoned to the court in Ctesiphon, resulting in Vahan regaining control of over the Armenian capital of Dvin, where he fortified himself.

[81][82][83] Ghazar highlights the opposition amongst his men towards the campaign, stating that the Iranian forces were demoralised at the prospect of facing the Hepthalites to the point of near mutiny.

[83] Akhshunwar, unwilling to face Peroz directly, had a large trench dug across the battleground, concealing it with shrubbery and loose wood, and positioning his forces behind it.

[93] The empire reached its lowest ebb: the shahanshah was now a client of the Hephthalites and was compelled to pay tribute; while the nobility and clergy exerted great influence and authority over the nation, being able to act as king-makers.

"[92] According to the Iranologist Ehsan Yarshater, some of the Iranian–Turanian battles that are described in the medieval Persian epic Shahnameh ('The Book of Kings') were seemingly based on the Hephthalite wars of Peroz and his successors.

[98] Since Bahram I (r. 271–274), the Sasanian monarchs had primarily resided in Gundeshapur in southern Iran, due to its convenient position between the Iranian plateau and the Mesopotamian plain.

The modern historian Jacob Neusner suggested that there may be some truth in the Iranian accounts, and that the Jews may had done it due to anticipating the coming of the Messiah, who was to arrive 400 years after the destruction of the Second Temple (dated by the rabbis in 68 AD, thus in 468).

[110][111] The iconography of the basilica showed Iranian characteristics, while its inscription, written in Old Georgian, mentions Peroz:[112] [With the help of the H]oly Trinity, the foundation of this holy church was laid in the twentieth [y]ear of [the reign of] King Pero[z] and was completed fifteen years [later].

[113] The wall, stretching from the Caspian coast to Pishkamar, was the largest of its time, and the biggest Iranian investment in military infrastructure in the late antique and medieval periods.

[115] The use of the mythological Kayanian title of kay, first used by Peroz's father Yazdegerd II, was due to a shift in the political perspective of the Sasanian Empire.

[116] The war against the Hunnic tribes may have awakened the mythical rivalry existing between the Iranian Kayanian rulers and their Turanian enemies, which is demonstrated in the Younger Avesta.

[116] This conflict between Iran and its eastern enemies may have resulted in the adoption of the title of kay, used by the Iranian mythical kings in their war against the Turanians in the east.

The Austrian historian and numismatist Nikolaus Schindel has suggested that gold coins were generally not used in daily lives, but instead used as a form of donation given to high-ranking Iranian magnates by the shahanshah, seemingly during festivities.