Yezdegird I 'The Wicked' born 380 (approx) and died in 420AD was ruler of the Sassanid empire from 399-420. He married the daughter of Soshandukt in 399 and the had (at least as far a records show) the one child, Bahram who as Bahram V (a.k.a. Varahan 'The Wild') suceeded his father to the throne.
At the start of his reign Christians had become to be tolerated, and were allowed to publicly worship and to build churches. Yezdegird came under increasing pressure from the Zoroastrian priesthood to cease condoning this; in about 416 the Christian Bishop Abdas forced the kings hand. Outraged at the idolatry inherent in the worship at The Temple of Fire, he and his followers (ironically enough), burned the temple down. This intolerance by the Christians of course forced the issue and Yezdegird ordered the bishop to rebuild the temple, or all the Christian churches would themselves be razed to the ground. Abdas refused, and true to his word Yezdegird destroyed all the churches and had Abdas put to death. This was the start of a further 40 years (mostly under his son's rule) of Christian persecution.