The mountains of Armenia and the course of the Euphrates separated the Eastern Empire from that of Persia. This country had been under the dominion of the people named Parthians at the time when the eagles of the Roman republic first appeared on the Euphrates, and defeat had more than once attended the Roman armies which attempted to enter their confines. Like every dominion not founded on the freedom of the people, that of the Arsacides (the Parthian royal line) grew feeble with time, and after a continuance of nearly five centuries the sceptre of Arsaces passed from the weak hand of the last monarch of his line to that of Ardeshir Babegan (that is the son of Babec), a valiant officer of the royal army, and a pretended descendant of the ancient monarchs of Persia. Ardeshir, to accomplish this revolution, availed himself of the religious prejudices of the Persian people. The Parthian monarchs had inclined to the manners and the religion of the Greeks, and the Light-religion--the original faith of Persia, and one of the purest and most spiritual of those to which a divine origin may not be assigned--had been held in slight estimation, and its priests unvisited by royal favour. It was the pride and the policy of Ardeshir to restore the ancient religion to the dignity which it had enjoyed under the descendants of Cyrus, and Religion, in return, lent her powerful aid to his plans of restoring the royal dignity to its pristine vigour, and of infusing into the breast of the people the love of country and the ardour for extending the Persian dominion to what it had been of old; and for 400 years the Sassanides[4] were the most formidable enemies of the Roman empire. But their dominion had, at the period of which we write, nearly attained the greatest limit allotted to Oriental dynasties; and though Noosheerwan the Just had attained great warlike fame, and governed with a vigour and justice that have made his name proverbial in the East, and Khoosroo Purveez displayed a magnificence which is still the theme of Persian poetry and romance, and carried his victorious arms over Syria and Egypt, and further along the African coast than even those of Darius I. had been able to advance, yet defeat from the gallant Emperor Heraclius clouded his latter days, and the thirteenth year after his death, by showing the Persian armies in flight, and the palladium of the empire, the jewel-set apron of the blacksmith Kawah, in the hands of the rovers of the deserts, revealed the secret that her strength was departed from Persia. The brilliancy of the early part of the reign of Khoosroo Purveez had been but the flash before death which at times is displayed in empires as in individuals. The vigour was gone which was requisite to stem the torrent of fanatic valour about to burst forth from the wilds of Arabia.