Expedition into Hyrcania. Alexander now took the soldiers who had been left behind in his pursuit and advanced into Hyrcania,471 which is the country lying on the left of the road leading to Bactra.472 On one side it is bounded by lofty mountains densely covered with wood, and on the other it is a plain stretching as far as the Great Sea473 in this part of the world. He led his army by this route, because he ascertained that the Grecian mercenaries serving under Darius had succeeded in escaping by it into the mountains of Tapuria; at the same time he resolved to subdue the Tapurians themselves. Having divided his army into three parts, he himself led the way by the shortest and most difficult route, at the head of the most numerous and at the same time the lightest division of his 188forces. He despatched Craterus at the head of his own brigade and that of Amyntas, some of the archers, and a few of the cavalry against the Tapurians; and he ordered Erigyius to take the Grecian mercenaries and the rest of the cavalry, and lead the way by the public thoroughfare, though it was longer, conducting the waggons, the baggage, and the crowd of camp-followers. After crossing the first mountains, and encamping there, he took the shield-bearing guards together with the lightest men in the Macedonian phalanx and some of the archers, and went along a road difficult and hard to travel upon, leaving guards for the roads wherever he thought there was any peril, so that the barbarians who held the mountains might not at those points fall upon the men who were following. Having passed through the defiles with his archers, he encamped in the plain near a small river474; and while he was here, Nabarzanes, the commander of Darius’s cavalry, Phrataphernes, the viceroy of Hyrcania and Parthia, and the other most distinguished of the Persians in attendance on Darius, arrived and surrendered themselves. After waiting four days ............