[Sidenote:  The sea route to the Orient.]

From the dawn of history the northern Indian Ocean was a thoroughfare.  Alexander the Great’s rediscovery of the old sea route to the Orient sounds like a modern event in relation to the gray ages behind it.  Along this thoroughfare Indian colonists, traders, and priests carried the elements of Indian civilization to the easternmost Sunda Isles; and Oriental wares, sciences and religions moved westward to the margin of Europe and Africa.  The Indian Ocean produced a civilization of its own, with which it colored a vast semi-circle of land reaching from Java to Abyssinia, and more faintly, owing to the wider divergence of race, the further stretch from Abyssinia to Mozambique.

Thus the northern Indian Ocean, owing to its form, its location in the angle between Asia and Africa and the latitude where, round the whole earth, “the zone of greatest historical density” begins, and especially its location just southeast of the Mediterranean as the eastern extension of that maritime track of ancient and modern times between Europe and China, has been involved in a long series of historical events.  From the historical standpoint, prior to 1492 it takes a far higher place than the Atlantic and Pacific, owing to its nature as an enclosed sea.[575] But like all such basins, this northern Indian Ocean attained its zenith of historical importance in early times.  In the sixteenth century it suffered a partial eclipse, which passed only with the opening of the Suez Canal.  During this interval, however, the Portuguese.  Dutch and English had rounded the Cape of Good Hope and entered this basin on its open or oceanic side.  By their trading stations, which soon traced the outlines of its coasts from Sofala in South Africa around to Java, they made this ocean an alcove of the Atlantic, and embodied its events in the Atlantic period of history.  It is this open or oceanic side which differentiates the Indian Ocean physically, and therefore historically, from a genuine enclosed sea.

[Sidenote:  Limitation of small area in enclosed seas.]

The limitation of every enclosed or marginal sea lies in its small area and in the relatively restricted circle of its bordering lands.  Only small peninsulas and islands can break its surface, and short stretches of coast combine to form its shores.  It affords, therefore, only limited territories as goals for expansion, restricted resources and populations to furnish the supply and demand of trade.  What lands could the Mediterranean present to the colonial outlook of the Greeks comparable to the North America of the expanding English or the Brazil of the Portuguese?  Yet the Mediterranean as a colonial field had great advantages in point of size over the Baltic, which is only one-sixth as large (2,509,500 and 431,000 square kilometers respectively), and especially over the Red Sea and Persian Gulf, whose effective areas were greatly reduced