After some delay at Susa—and after confirming the Persian Abulites, who had surrendered the city, in his satrapy, yet not without two Grecian officers as guarantees, one commanding the military force, the other governor of the citadel—Alexander crossed the river Eulæus or Pasitigris, and directed his march to the south-east towards Persis proper, the ancient hearth or primitive seat from whence the original Persian conquerors had issued.[411] Between Susa and Persis lay a mountainous region occupied by the Uxii—rude but warlike shepherds, to whom the Great King himself had always been obliged to pay a tribute whenever he went from Susa to Persepolis, being unable with his inefficient military organization to overcome the difficulties of such a pass held by an enemy. The Uxii now demanded the like tribute from Alexander, who replied by inviting them to meet him at their pass and receive it. Meanwhile a new and little frequented mountain track had been made known to him, over which he conducted in person a detachment of troops so rapidly and secretly as to surprise the mountaineers in their own villages. He thus not only opened the usual mountain pass for the transit of his main army, but so cut to pieces and humiliated the Uxii, that they were forced to sue for pardon. Alexander was at first disposed to extirpate or expel them; but at length, at the request of the captive Sisygambis, permitted them to remain as subjects of the satrap of Susa, imposing a tribute of sheep, horses, and cattle, the only payment which their poverty allowed.[412] [411] Arrian, iii. 17, 1. Ἄρας δὲ ἐκ Σούσων, καὶ διαβὰς τὸν Πασιτίγρην ποταμὸν, ἐμβάλλει εἰς τὴν Οὐξίων γῆν. The Persian Susa was situated between two rivers; the Choaspes (now Kherkha) on the west; the Eulæus or Pasitigris, now Karun, on the east; both rivers distinguished for excellent water. The Eulæus appears to have been called Pasitigris in the lower part of its course—Pliny, H. N. xxxi. 21. “Parthorum reges ex Choaspe et Eulæo tantum bibunt.” Ritter has given an elaborate exposition respecting these two rivers and the site of the Persian Susa (Erdkunde, part ix. book iii. West-Asien, p. 291-320). [412] Arrian, iii. 17; Curtius. v. 3, 5-12; Diodor. xvii. 67; Strabo, xv. p. 729. It would seem that the road taken by Alexander in this march, was that described by Kinneir, through Bebahan and Kala-Sefid to Schiraz (Geographical Memoir of the Persian Empire, p. 72). Nothing can exceed the difficulties of the territory for military operation. No certainty is attainable, however, respecting the ancient geography of these regions. Mr. Long’s Map of Ancient Persia shows how little can be made out.