The season of the year was impracticable for navigation from the prevalence of the Etesian winds, which do not blow there as with us from the north, but come as a south wind from the Great Ocean. It was ascertained that from the beginning of winter, that is from the setting of the Pleiades,[190] till the winter solstice, the weather was suitable for making voyages, because the mild breezes which then blow steadily seaward from the land, which is drenched by this time with heavy rains, favour coasting voyages, whether made by oar or by sail. Nearchos, who had been appointed to the command of the fleet, was waiting for the season for coasting, but Alexander set out from Patala, and advanced with the whole of his army to the river Arabios.[191] He then took half of the hypaspists and archers, the infantry brigades called foot companions, the corps of companion cavalry, and a squadron from each division of the other cavalry, and all the horse archers, and turned towards the sea, which lay on the left, not only to dig as many wells as possible for the use of the expedition while coasting those shores, but also to fall suddenly upon the Oreitai (an Indian tribe in those parts which had long been independent), because they had rendered no friendly service either to himself or the army. The command of the troops which he did not take with him was entrusted to Hêphaistiôn. There was settled near the river Arabios another[192] independent tribe called the Arabitai, and, as these neither thought themselves a match for Alexander, nor yet wished to submit to him, they fled into the desert when they learned that he was marching against them. But Alexander having crossed the Arabios, which was neither broad nor deep, traversed the most of the desert, and found himself by daybreak near the inhabited country. Then leaving orders with the infantry to follow him in regular line, he set forward with the cavalry, which he divided into squadrons, to be spread over a wide extent of the plain, and it was thus he marched into the country of the Oreitai.[193] All who turned to offer resistance were cut down by the cavalry, but many were taken prisoners. He then encamped near a small sheet of water, and on being joined by the troops under Hêphaistiôn still continued his progress, and arrived at the village called Rambakia,[194] which was the largest in the dominions of the Oreitai. He was pleased with the situation, and thought that if he colonised it, it would become a great and prosperous city. He therefore left Hêphaistiôn behind him to carry this scheme into effect. _Chapter XXII.—Submission of the Oreitai—Description of the Gadrôsian desert_