This was of so high importance to Bahram II, that he allegedly himself went to Mtskheta in order to secure Mirian's position. He also sent one of his grandees named Mirvanoz (also a Mihranid) to the country in order to act as the guardian of Mirian, who was then merely aged seven. Other branches of the Mihranid family were a few decades later established on other Caucasian thrones, one of them being in Gogarene, and the other in the Armeno-Albanian principality of Gardman. The "Life of the Kings" recount Mirian's reign in much details. While its information about Mirian’s participation—as an Iranian client king—in the Sasanid war against the Roman Empire, and territorial ambitions in Armenia can be true, the claims of Mirian’s being a pretender to the throne of Iran, his being in control of Colchis and Albania, and expansion of his activity as far as Syria is obviously fictional. Mirian inherited a kingdom that had been ruling Iberia since the 4th century BC. Iberia, like the rest of the Caucasus, was dominated by Iranian cultures and mixtures of the Zoroastrian religion. Indeed, according to the modern historian Stephen H. Rapp, the Caucasus was part of the "Iranian Commonwealth", "a massive cross-cultural enterprise stretching from Central Asia to the Balkans." Mirian, as a Sasanian vassal, took part in shah Narseh's brief war against the Romans from 297 to 298. The war ended with a crushing Sasanian defeat, forcing Narseh to cede Armenia and Iberia to the Romans. Mirian quickly adapted to this change in political situation, and established close ties with Rome. This association was cemented by Mirian's conversion to Christianity—according to tradition—through the ministry of Nino, a Cappadocian nun. Nevertheless, as Ammianus Marcellinus recounts, Constantine's successor, Constantius, had to send in 360 embassies with costly presents to Arsaces of Armenia and Meribanes of Iberia to secure their allegiance during the confrontation with Iran. Mirian's conversion to Christianity might have occurred in 334, followed by the declaration of Christianity as Iberia's state religion in 337. He was, thus, among the first monarchs of the ancient world to have adopted this new religion. A legend has it that when Mirian, staunchly pagan, was hunting in the woods near his capital Mtskheta, the darkness fell upon the land and the king was totally blinded.