The double and treble ditches were filled with a stream of water; and in the management of the river, the most skilful labor was employed to supply the inhabitants, to distress the besiegers, and to prevent the mischiefs of a natural or artificial inundation. Dara continued more than sixty years to fulfil the wishes of its founders, and to provoke the jealousy of the Persians, who incessantly complained, that this impregnable fortress had been constructed in manifest violation of the treaty of peace between the two empires. Between the Euxine and the Caspian, the countries of Colchos, Iberia, and Albania, are intersected in every direction by the branches of Mount Caucasus; and the two principal _gates_, or passes, from north to south, have been frequently confounded in the geography both of the ancients and moderns. The name of _Caspian_ or _Albanian_ gates is properly applied to Derbend, which occupies a short declivity between the mountains and the sea: the city, if we give credit to local tradition, had been founded by the Greeks; and this dangerous entrance was fortified by the kings of Persia with a mole, double walls, and doors of iron. The _Iberian_ gates are formed by a narrow passage of six miles in Mount Caucasus, which opens from the northern side of Iberia, or Georgia, into the plain that reaches to the Tanais and the Volga. A fortress, designed by Alexander perhaps, or one of his successors, to command that important pass, had descended by right of conquest or inheritance to a prince of the Huns, who offered it for a moderate price to the emperor; but while Anastasius paused, while he timorously computed the cost and the distance, a more vigilant rival interposed, and Cabades forcibly occupied the Straits of Caucasus. The Albanian and Iberian gates excluded the horsemen of Scythia from the shortest and most practicable roads, and the whole front of the mountains was covered by the rampart of Gog and Magog, the long wall which has excited the curiosity of an Arabian caliph and a Russian conqueror. According to a recent description, huge stones, seven feet thick, and twenty-one feet in length or height, are artificially joined without iron or cement, to compose a wall, which runs above three hundred miles from the shores of Derbend, over the hills, and through the valleys of Daghestan and Georgia. Without a vision, such a work might be undertaken by the policy of Cabades; without a miracle, it might be accomplished by his son, so formidable to the Romans, under the name of Chosroes; so dear to the Orientals, under the appellation of Nushirwan. The Persian monarch held in his hand the keys both of peace and war; but he stipulated, in every treaty, that Justinian should contribute to the expense of a common barrier, which equally protected the two empires from the inroads of the Scythians.