It appears that even after this discovery he had no new views on Alexandria. He indeed had, in general, the plan of establishing a trade between the Indies and the western parts of his empire ; but he had too little knowledge to be able to form the plan to conduct this trade through Egypt. He had seen the Indus, he had seen the Nile, but he did not know the seas of Arabia, which are in between. Scarcely had he arrived from the Indies before he had new fleets built and sailed  on the Eulæus, the Tigris, the Euphrates, and the sea ; he removed the falls which the Persians had installed on these rivers ; he discovered that the gulf of Persia was a gulf of the ocean. As he went to explore that sea,  after having explored the Indian sea ; as he had a port built in Babylon for a thousand vessels, and arsenals ; as he sent five hundred talents to Phoenicia and Syria to bring navigators whom he wished to place in the colonies he was scattering along the coasts ; finally, as he made immense constructions on the Euphrates and other rivers of Assyria, it cannot be doubted that his design was to ply the Indian trade through Babylon and the Persian Gulf.
Some persons, on the pretext that Alexander wanted to conquer Arabia,  have said that he had conceived the design of locating the seat of his empire there ; but how could he have chosen a place that was unfamiliar to him ?  Besides, it was the most inconvenient country in the world : he would have separated himself from his empire. The caliphs, who conquered afar, promptly abandoned Arabia to settle elsewhere.