- After the death of Yazdegard II, his two sons, Piruz and Hormazd, both contested the throne. While Piruz was absent as Governor in Seistan, the younger brother, declared himself King Hormazd III. Piruz, with the help of a large Hephthalite army, defeated Hormazd in battle and took the throne (459 A.D.).
- Piruz was more intolerant of the Jews than his father. He passed a decree that all orphaned Jews were to be brought up as Zarathushtrians.
- During the two years while Hormazd III had ruled there had been unrest in Ardan (Albania). The Governor, Vatche (a son of Piruz's sister) threw off his allegiance and declared Ardan independent. In 459, with the help of his Hephthalite allies Piruz subjugated the province.
- Due to a 7 year long drought, Piruz remitted taxes to help pay for grain that had to be imported from India, and elsewhere. As a result, he had difficulties in making his annual payment of the reward due to the Hephthalites for their help. The Hephthalite Chief, Khush Nawaz was further antagonized by Piruz when he sent a commoner, instead of his daughter in hand of marriage. In the war that followed, there were some early gains but through treachery the Hephthalites captured Piruz and his son, Kavad.
- In 465 the Roman emperor, Leo I (457-474 ) arranged for the release of Piruz on condition his son, Kavad was left hostage. In addition Piruz was forced to pay homage to the chief and swear never to invade Hephthalite territory again beyond a certain pillar on the banks of the Oxus.
- Between 481-483, a revolt in Armenia fomented by the Roman emperor Zeno (474-491) in protest over the persecution of Christians was eventually put down by Piruz.
- In 484 another branch of the Hephthalites under the command of Khingila Khan attacked the Kushan Capital, Balkh. Piruz marched with 100,000 men, 500 Elephants and his Cavalry. Piruz kept the oath he had taken by having one his elephants carry the pillar ahead of his army. Again through deceit, the Hephthalites won. Piruz was defeated when his army was enticed into area containing deep trenches, camouflaged by foliage where the elephants were trapped. Piruz sustained severe wounds from which he died.