It is difficult to understand this sudden conclusion of peace by a young prince, evidently anxious to reap laurels, who in the first year of his reign had, at the head of a large army, invaded the dominions of a neighbor. The Roman account, that he invaded, that he was practically unopposed, and that then, out of politeness towards the prefect of the East, he voluntarily retired within his own frontier, “having done nothing disagreeable,” is as improbable a narrative as we often meet with, even in the pages of the Byzantine historians. Something has evidently been kept back. If Isdigerd returned, as Procopius declares, without effecting anything, he must have been recalled by the occurrence of troubles in some other part of his empire. But it is, perhaps, as likely that he retired, simply because he had effected the object with which he engaged in the war. It was a constant practice of the Romans to advance their frontier by building strong towns on or near a debatable border, which attracted to them the submission of the neighboring district. The recent building of Theodosiopolis in the eastern part of Roman Armenia had been an instance of this practice. It was perhaps being pursued elsewhere along the Persian border, and the invasion of Isdigerd may have been intended to check it. If so, the proviso of the treaty recorded by Procopius would have afforded him the security which he required, and have rendered it unnecessary for him to continue the war any longer. His arms shortly afterwards found employment in another quarter. The Tatars of the Transoxianian regions were once more troublesome; and in order to check or prevent the incursions which they were always ready to make, if they were unmolested, Isdigerd undertook a long war on his northeastern frontier, which he conducted with a resolution and perseverance not very common in the East. Leaving his vizier, Mihr-Narses, to represent him at the seat of government, he transferred his own residence to Nishapm, in the mountain region between the Persian and Kharesmian deserts, and from that convenient post of observation directed the military operations against his active enemies, making a campaign against them regularly every year from A.D. 443 to 451. In the year last mentioned he crossed the Oxus, and, attacking the Ephthalites in their own territory, obtained a complete success, driving the monarch from the cultivated portion of the country, and forcing him to take refuge in the desert. So complete was his victory that he seems to have been satisfied with the result, and, regarding the war as terminated, to have thought the time was come for taking in hand an arduous task, long contemplated, but not hitherto actually attempted.