between the two empires. There is no difficulty in conceiving the intention of the Roman princes to improve their revenue by some restraints upon commerce; but as Nisibis was situated within their own dominions, and as they were masters both of the imports and exports, it should seem that such restraints were the objects of an internal law, rather than of a foreign treaty. To render them more effectual, some stipulations were probably required on the side of the king of Persia, which appeared so very repugnant either to his interest or to his dignity, that Narses could not be persuaded to subscribe them. As this was the only article to which he refused his consent, it was no longer insisted on; and the emperors either suffered the trade to flow in its natural channels, or contented themselves with such restrictions, as it depended on their own authority to establish. As soon as this difficulty was removed, a solemn peace was concluded and ratified between the two nations. The conditions of a treaty so glorious to the empire, and so necessary to Persia Persian, may deserve a more peculiar attention, as the history of Rome presents very few transactions of a similar nature; most of her wars having either been terminated by absolute conquest, or waged against barbarians ignorant of the use of letters. I. The Aboras, or, as it is called by Xenophon, the Araxes, was fixed as the boundary between the two monarchies. That river, which rose near the Tigris, was increased, a few miles below Nisibis, by the little stream of the Mygdonius, passed under the walls of Singara, and fell into the Euphrates at Circesium, a frontier town, which, by the care of Diocletian, was very strongly fortified. Mesopotomia, the object of so many wars, was ceded to the empire; and the Persians, by this treaty, renounced all pretensions to that great