and Gelani, probably the Euseni and the Vertse.  The Chionites are thought to have been Hiongnu or Huns; and the Euseni are probably the Usiun, who, as early as B.C. 200, are found among the nomadic hordes pressing towards the Oxus.  The Vertse are wholly unknown.  The Gelani should, by their name, be the inhabitants of Ghilan, or the coast tract south-west of the Caspian; but this locality seems too remote from the probable seats of the Chionites and Euseni to be the one intended.  The general scene of the wars was undoubtedly east of the Caspian, either in the Oxus region, or still further eastward, on the confines of India and Scythia.  The result of the wars, though not a conquest, was an extension of Persian influence and power.  Troublesome enemies were converted into friends and allies.  The loss of a predominating influence over Armenia was thus compensated, or more than compensated, within a few years, by a gain of a similar kind in another quarter.

While Sapor was thus engaged in the far East, he received letters from the officer whom he had left in charge of his western frontier, informing him that the Romans were anxious to exchange the precarious truce which Mesopotamia had been allowed to enjoy during the last five or six years for a more settled and formal peace.  Two great Roman officials, Cassianus, duke of Mesopotamia, and Musonianus, Praetorian prefect, understanding that Sapor was entangled in a bloody and difficult war at the eastern extremity of his empire, and knowing that Constantius was fully occupied with the troubles caused by the inroads of the barbarians into the more western of the Roman provinces, had thought that the time was favorable for terminating the provisional state of affairs in the Mesopotamian region by an actual treaty.  They had accordingly opened negotiations with Tamsapor, satrap of Adiabene, and suggested to him that he should sound his master on the subject of making peace with Rome.  Tamsapor appears to have misunderstood the character of these overtures, or to have misrepresented them to Sapor; in his despatch he made Constantius himself the mover in the matter, and spoke of him as humbly supplicating the great king to grant him conditions.  It happened that the message reached Sapor just as he had come to terms with his eastern enemies, and had succeeded in inducing them to become his allies.  He was naturally elated at his success, and regarded the Roman overture as a simple acknowledgment of weakness.  Accordingly he answered in the most haughty style.  His letter, which was conveyed to the Roman emperor at Sirmium by an ambassador named Narses, was conceived in the following terms: