Detailed summary of the article : "Ἡ μεγάλη θάλασσα : un autre nom de l’Érythrée?" Section 1 (introduction): the names of the Indian Ocean in Greco-Roman antiquity In Greek and Roman antiquity the modern Indian Ocean was given various names, of which S. Sidebotham provides a short but "rather representative" catalogue in his study of Roman economic policy (S.E. Sidebotham, Roman Economic Policy in the Erythra Thalassa 30 B.C.- A.D., Leiden, 1986, Appendix A, p. 182-3). Besides the most common names, namely Erythra thalassa / mare Rubrum (= the Red Sea) and Indikê thalassa / mare Indicum (= the Indian Sea), S. Sidebotham lists some less attested designations, such as Megalê thalassa (= the Great Sea"). Two pieces of evidence (Arrian, Anab., 5, 4, 1 ; Diodorus of Sicily, 2, 35, 1), Sidebotham writes, support the view that Megalê thalassa is to be equated with the Indian Ocean / Erythra thalassa (p. 182 : "Megale thalassa = Indian Ocean"). This article aims at examining the accuracy of the author's statement. Section 2 : the name Megalê thalassa in Arrian's works Besides the passage mentioned by Sidebotham (Arrian, Anab. 5, 4, 1 : "The Indus is the largest of all the rivers in Asia and Europe, except the Ganges, which is also an Indian river. It takes its rise on this side mount Parapamisus, or Caucasus, and discharges its water into the Great Sea which lies near India in the direction of the south wind."), several other occurrences of this name can be found in Arrian's writings 1 : • Anab. 5, 6, 3 : "They (i.e. Eratosthenes and Megasthenes) say that India is bounded towards the east and the east wind as far as the south by the Great Sea, towards the north by mount Caucasus, as far as its junction with the Taurus; and that the river Indus cuts it off towards the west and the north-west wind, as far as the Great Sea." • Ind. 2, 5 : "The western part of India is bounded by the river Indus right down to the Great Sea, where the river runs out by two mouths." • Ind. 3, 2 : "He states that beginning with Mount Taurus, where are the springs of the river Indus, along the Indus to the Great Sea, and to the mouths of the Indus, the side of India is thirteen thousand stades in length." • Anab. 6, 1, 1 : "Alexander now resolved to sail down the Hydaspes to the Great Sea, after he had prepared on the banks of that river many thirty-oared galleys and others with one and a half bank of oars ..." • Anab. 6, 1, 5-6 : "However, when he (= Alexander) had made a more careful inquiry into the facts relating to the river Indus, he learned the following details from the natives : that the Hydaspes unites its water with the Acesines, as the latter does with the Indus, and that they both yield up their names to the Indus; that the last-named river has two mouths, through which it discharges itself into the Great Sea; but that it has no connection with the Egyptian country. He then removed from the letter to his mother the part he had written about the Nile. Planning a voyage down the rivers as far as the Great Sea, he ordered ships for this purpose to be prepared for him. The crews of his ships were fully supplied from the Phoenicians, Cyprians, Carians, and Egyptians who accompanied the army. In view of this set of documents, it seems to be beyond doubt that the name Megalê thalassa relates to the sea bordering India, and especially to the part in which the river Indus terminates. Thus Sidebotham's opinion seems to be corroborated by such textual evidence. Section 3 : the true meaning of the name Megalê thalassa in Arrian's writings In fact the list appearing above is by no means exhaustive : Arrian refers to the Megalê thalassa on 1 All translations are taken from the websites "Alexander the Great - sources" and "Perseus"