Having held this interview with Apharban, Galerius hastened to meet and consult his colleague.  Diocletian had remained in Syria, at the head of an army of observation, while Galerius penetrated into Armenia and engaged the forces of Persia.  When he heard of his son-in-law’s great victory he crossed the Euphrates, and advancing through Western Mesopotamia, from which the Persians probably retired, took up his residence at Nisibis, now the chief town of these parts.  It is perhaps true that his object was “to moderate, by his presence and counsels, the pride of Galarius.”  That prince was bold to rashness, and nourished an excessive ambition.  He is said to have at this time entertained a design of grasping at the conquest of the East, and to have even proposed to himself to reduce the Persian Empire into the form of a Roman province.  But the views of Diocletian were humbler and more prudent.  He held to the opinion of Augustus and Hadrian, that Rome did not need any enlargement of her territory, and that the absorption of the East was especially undesirable.  When he and his son-in-law met and interchanged ideas at Nisibis, the views of the elder ruler naturally prevailed; and it was resolved to offer to the Persians tolerable terms of peace.  A civilian of importance, Sicorius Probus, was selected for the delicate office of envoy, and was sent, with a train of attendants, into Media, where Narses had fixed his headquarters.  We are told that the Persian monarch received him with all honor, but, under pretence of allowing him to rest and refresh himself after his long journey, deferred his audience from day to day; while he employed the time thus gained in collecting from various quarters such a number of detachments and garrisons as might constitute a respectable army.  He had no intention of renewing the war, but he knew the weight which military preparation ever lends to the representations of diplomacy.  Accordingly it was not until he had brought under the notice of Sicorius a force of no inconsiderable size that he at last admitted him to an interview.  The Roman ambassador was introduced into an inner chamber of the royal palace in Media, where he found only the king and three others—­Apharban, the envoy sent to Galerius, Archapetes, the captain of the guard, and Barsaborsus, the governor of a province on the Armenian frontier.  He was asked to unfold the particulars of his message, and say what were the terms on which Rome would make peace.  Sicorius complied.  The emperors, he said, required five things:—­(i.) The cession to Rome of five provinces beyond the river Tigris, which are given by one writer as Intilene, Sophene, Arzanene, Carduene, and Zabdicene; by another as Arzanene, Moxoene, Zabdicene, Rehimene, and Corduene; (ii.) the recognition of the Tigris, as the general boundary between the two empires; (iii.) the extension of Armenia to the fortress of Zintha, in Media; (iv.) the relinquishment by Persia to Rome of her protectorate over Iberia, including the right of giving investiture to the Iberian kings; and (v.) the recognition of Nisibis as the place at which alone commercial dealings could take place between the two nations.