Yazdegerd I was a highly intelligent ruler, who tried to emancipate himself from the dominion of the magnates and the Magian priests. He punished the nobles severely when they attempted oppression; he granted Christians their own organization.
With the Roman Empire Yazdegerd I lived in peace and friendship, and is therefore as much praised by the Byzantine authors.
After a reign of twenty-two years he appears to have been murdered in Khorasan.