However, I shall treat of the Indians in a separate work,[82] in which I shall set down whatever seems to be most credible in the reports supplied by those who accompanied Alexander in his expedition, and by Nearchos who made a voyage round the Great Sea which adjoins the Indians. I shall then add the accounts of the country which were compiled by Megasthenes and Eratosthenês, who are both writers of standard authority. I shall describe the customs of the Indians and the remarkable animals which their country is said to produce, and also the voyage which was made by Nearchos in the outer sea.[83] In the meantime it will suffice if I content myself with describing only what seems requisite to make the account of Alexander’s operations clearly intelligible. Mount Tauros divides Asia, beginning from Mykalê, the mountain which lies opposite to the island of Samos; then forming the boundary of the country of the Pamphylians and Kilikians, it stretches onwards to Armenia. From the Armenians it passes into Mêdia, and runs through the country of the Parthians and the Khorasmians. Reaching Baktria it there unites with Mount Parapamisos, which the Macedonians of Alexander’s army called the Kaukasos, for the purpose, it is said, of magnifying the deeds of Alexander, for it could thus be said that he had carried his victorious arms even beyond the Kaukasos. It is possible, however, that this mountain range may be a continuation of that other Kaukasos which is in Skythia, in the same way as it is a continuation of the Tauric range. For this reason I have before this occasionally called this range Kaukasos, and in future I mean to call it so. This Kaukasos extends as far as the great Indian Ocean in the direction of the east.[84] All the important rivers of Asia accordingly rise either in Mount Tauros or Mount Kaukasos, and shape their courses some to the north, and others to the south. Those which run northward discharge their waters either into the Maiôtic Lake, or into the Hyrkanian Sea, which is in reality a gulf of the Great Sea.[85] The rivers which run southward are the Euphrates, Tigris, Indus, Hydaspês, Akesines, Hydraôtes, and Hyphasis, together with the rivers between these and the Ganges. All these either enter the sea, or, like the Euphrates, disappear among the swamps which receive their waters. _Chapter VI.—Position and boundaries of India and how its plains may have been formed_