The reality of this voyage, or at least the accuracy of some of the particulars it records, has been doubted.  Scylax describes the course of the Indus to the east; whereas it runs to the south-west.  It is also worthy of remark, that as Darius, before the voyage of Scylax, was master of the Attock, Peukeli, and Multan, he needed no information respecting the route to India, as every conqueror has followed this very obvious and easy route.  Dr. Vincent also objects to the authority of this voyage, or rather to the track assigned to it:  “I cannot believe,” he observes, “from the state of navigation in that age, that Scylax could perform a voyage round India, from which the bravest of Alexander’s navigators shrunk, or that men who had explored the desert coast of Gadrosia, should be less daring than an experienced native of Caryandria.  They returned with amazement from the sight of Mussenden and Ras-al-had, while Scylax succeeded without a difficulty upon record.  But the obstacles to such a voyage are numerous; first, whether Pactzia be Peukeli, and Caspatyrus, Multan:  secondly, if Darius were master of Multan, whether he could send a ship or a fleet down the sea, through tribes, where Alexander fought his way at every step:  thirdly, whether Scylax had any knowledge of the Indian Ocean, the coast, or the monsoon:  fourthly, if the coast of Gadrosia were friendly, which is doubtful, whether he could proceed along the coast of Arabia, which must be hostile from port to port:  these and a variety of other difficulties which Nearchus experienced, from famine, from want of water, from the construction of his ships, and from the manners of the natives, must induce an incredulity in regard to the Persian account, whatever respect we may have to the fidelity of Herodotus.”

Such are the objections urged by Dr. Vincent to the authority of this voyage.  In some of the particular objections there may be considerable force; but with respect to the general ones, from the manners or hostility of the natives inhabiting the coasts along which the voyage was performed, they apply equally to the voyages of the Carthaginians along the western coasts of Africa and Europe, and indeed to all the voyages of discovery, or distant voyages of the ancients.  It may be added, that according to Strabo, Posidonius disbelieved the whole history of Scylax.  In the Geographi Minores of Hudson, a voyage ascribed to Scylax is published; but great doubts are justly entertained on the subject of its authenticity.  Dodwell is decidedly against it.  The Baron de Sainte Croix, in a dissertation read before the Academy of Inscriptions, defends the work which bears the name of Scylax as genuine.  Dr. Vincent states one strong objection to its authenticity:  mention is made in it of Dardanus, Rhetium, and Illium, in the Troad; whereas there is great doubt whether Rhetium was in existence in the time of the real Scylax:  besides, it is remarkable that nothing is said respecting India in the treatise now extant.  That the original and genuine work described India is, however, undoubted, on the authority of Aristotle, who mentions that there was such a person as Scylax, that he had been in India, and that his account of that country was extant in his (Aristotle’s) time.