The last of the kings of this dynasty who ruled over Persia was the ally and kinsman of the father of King Tiridates, who was destined, after much vicissitude of fortune, to embrace Christianity and to adopt it as the religion of the State. Ardavan and Chosroes were seated on the thrones of Persia and Armenia, when a prince of the Persian province which is now known under the name of Fars (Shiraz, Persepolis) overthrew the former of these monarchs by a decisive battle, in which Ardavan himself was slain (A.D. 227). The victor, Ardashir, became master of the great Persian monarchy in which the king of Armenia held the second place. His dynasty, the Sasanian, supplanted the Arsakids in Persia, and continued to rule until the middle of the seventh century, when it succumbed to the Arabs and to Islam. The Sasanians are familiar to all of us as the permanent enemies of the Roman Empire; and the traveller may be said to be on terms of intimacy with them, for they have left him several monuments of great solidity and architectural merit which mock the squalor of their surroundings at the present day. These, it is true, they erected with the aid of architects and artisans taken captive in their wars with the Empire. [199] Fars was in those days a centre of Zoroastrianism or Mazdaism; and Ardashir was the champion of the fire-worshippers, leaned on their support and closely identified them with his dynasty. When the news of the death of his kinsman and ally was brought to the Arsakid king of Armenia, profound grief filled the soul of Chosroes. For the moment he was powerless to arrest the triumph of the usurper; but in the following year (A.D. 228) he had matured extensive preparations, and, at the head of an army which comprised Huns from beyond Caucasus as well as other nomads, marched to the frontiers of Persia and laid waste her provinces to the gates of Ctesiphon. Thirsting to avenge his race, he endeavoured to enlist the Parthian satraps in the empire of Ardashir; but these temporising or jealous princelets had thrown in their lot with the Sasanian monarch and could not be induced to stir. He was, however, assisted by a portion of the Medes and by the sons of Ardavan. [200]