(ii.) The Tigris is said by Patricius and Festus to have been made the boundary of the two empires. Gibbon here boldly substitutes the Western Khabour and maintains that “the Roman frontier traversed, but never followed, the course of the Tigris.” He appears not to be able to understand how the Tigris could be the frontier, when five provinces across the Tigris were Roman. But the intention of the article probably was, first, to mark the complete cession to Rome of Eastern as well as Western Mesopotamia, and, secondly, to establish the Tigris as the line separating the empires below the point down to which the Romans held both banks. Cordyene may not have touch the Tigris at all, or may have touched it only about the 37th parallel. From this point southwards, as far as Mosul, or Nimrud, or possibly Kileh Sherghat, the Tigris was probably now recognized as the dividing line between the empires. By the letter of the treaty the whole Euphrates valley might indeed have been claimed by Rome; but practically she did not push her occupation of Mesopotamia below Circeshim. The real frontier from this point was the Mesopotamian desert, which extends from Kerkesiyeh to Nimrud, a distance of 150 miles. Above this it was the Tigris, as far probably as Feshapoor; after which it followed the line, whatever it was, which divided Oordyene from Assyria and Media. (iii.) The extension of Armenia to the fortress of Zintha, in Media, seems to have imported much more than would at first sight appear from the words. Gibbon interprets it as implying the cession of all Media Atropatene, which certainly appears a little later to be in the possession of the Armenian monarch, Tiridates. A large addition to the Armenian territory out of the Median is doubtless intended; but it is quite impossible to determine definitely the extent or exact character of the cession.