When Alexander the Great marched over to India towards the end of the 4th century B.C. and incorporated a section of this country in his Empire, it was not the first time that the ancient Greeks were learning about this part of the world, for they had known quite a lot about it already from centuries before. Indian words for various products from that country are to be found in Greek literature prior to the 4th century B.C., and even Homer shows awareness of a certain people living in the Far East whom he vaguely calls “Ethiopians”. Knowledge of this region increased at the end of the 6th century B.C. when a Greek from Ionia, by the name of Scylax, was sent by the Persian king to explore the Indus valley. He completed this voyage and wrote a book about what he saw.
His work was used by Hecataeus, a fellow Greek from Ionia, around the beginning of the 5th century B.C., when he decided to include a section about India in a geographical book which he was writing. Hecataeus’ work was, in turn, used by Herodotus, who also wrote a few chapters on India in his Histories, towards the end of the 5th century B.C. An examination of these three authors will show that the ancient Greeks, prior to Alexander’s expedition, knew not only about the topography, climate, and creatures of this country, but also about the inhabitants, their customs, and, in some cases, their names. Their knowledge, in fact, extended so far so as to even include the names of some of India’s cities and regions. Alexander the Great, in other words, when he reached India, was not revealing to the Greeks of his time a country about which they knew nothing, but was rather expanding the knowledge which they already had.
M.A. Thesis, University of British Columbia (1992)