Alexander, with his own half of the army, undertook the reduction of the Aspasii, the Guræi, and the Assakeni, tribes occupying mountainous and difficult localities along the southern slopes of the Hindoo-Koosh; but neither they nor their various towns mentioned—Arigæon, Massaga, Bazira, Ora, Dyrta, etc., except perhaps the remarkable rock of Aornos,[535] near the Indus—can be more exactly identified. These tribes were generally brave, and seconded by towns of strong position as well as by a rugged country, in many parts utterly without roads.[536] But their defence was conducted with little union, no military skill, and miserable weapons; so that they were no way qualified to oppose the excellent combination and rapid movements of Alexander, together with the confident attack and very superior arms, offensive, as well as defensive, of his soldiers. All those who attempted resistance were successively attacked, overpowered and slain. Even those who did not resist, but fled to the mountains, were pursued, and either slaughtered or sold for slaves. The only way of escaping the sword was to remain, submit, and await the fiat of the invader. Such a series of uninterrupted successes, all achieved with little loss, it is rare in military history to read. The capture of the rock of Aornos was peculiarly gratifying to Alexander, because it enjoyed the legendary reputation of having been assailed in vain by Herakles—and indeed he himself had deemed it, at first sight, unassailable. After having thus subdued the upper regions (above Attock or the confluence of the Kabul river) on the right bank of the Indus, he availed himself of some forests alongside to fell timber and build boats. These boats were sent down the stream, to the point where Hephæstion and Perdikkas were preparing the bridge.[537] [535] Respecting the rock called Aornos, a valuable and elaborate article, entitled “Gradus ad Aornon” has been published by Major Abbott in the Journal of the Asiatic Society of Bengal, No. iv. 1854. This article gives much information, collected mainly by inquiries on the spot, and accompanied by a map, about the very little known country west of the Indus, between the Kabool river on the south, and the Hindoo-Koosh on the north.