This state of things could not have been pleasing to the Greek princes of Bactria, who must have felt that the reaction towards barbarism in these parts tended to isolate them, and that there was a danger of their being crushed between the Parthians on the one hand and the perpetually advancing Indians on the other. When Antiochus the Great, after concluding his treaty with Euthydemus, marched eastward, the Bactrian monarch probably indulged in hopes that the Indians would receive a check, and that the Greek frontier would be again carried to the Indus, if not to the Sutlej. But, if so, he was disappointed. Antiochus, instead of making war upon the Indians, contented himself with renewing the old alliance of the Seleucidae with the Maurja princes, and obtaining a number of elephants from Sophagesenus, the grandson of Sandracottus. It is even possible that he went further, and made cessions of territory in return for this last gift, which brought the Indian frontier still nearer than before to that of Bactria, At any rate, the result of the Indian expedition of Antiochus seems to have been unsatisfactory to Euthydemus, who shortly afterwards commenced what are called “Indian Wars” on his south-eastern frontier, employing in them chiefly the arms of his son, Demetrius. During the latter years of Euthydemus and the earlier ones of Demetrius, the Bactrian rule was rapidly extended over the greater portion of the modern Afghanistan; nor did it even stop there. The arms of Demetrius were carried across the Indus into the Punjaub region; and the city of Euthymedeia upon the Hydaspes remained to later times an evidence of the extent of his conquests. From B.C. 206 to about B.C. 185 was the most flourishing period of the Bactrian monarchy, which expanded during that space from a small kingdom into a considerable empire. The power and successes of the Bactrian princes at this time account sufficiently for the fact that the contemporary Parthian monarchs stood upon their guard, and undertook no great expeditions. Arsaces III., who continued on the throne for about ten or twelve years after his peace with Antiochus, and Priapatius, or Arsaces IV., his son, who succeeded him, and had a reign of fifteen years, were content, as already observed, to watch over their own State, husbanding its resources, and living at peace with all their neighbors. It was not till Phraates I. (Arsaces V.), the son of Priapatius, had mounted the throne, B.C. 181, that this policy was departed from, and Parthia, which had remained tranquil for a quarter of a century, once more aroused herself, and assumed an attitude of aggression.