It is probably from the Babylonians that the Greeks obtained the idea of an all-encircling ocean. Inhabitants of Mesopotamia would find themselves reaching the ocean in almost any direction in which they travelled, either the Caspian, the Black Sea, the Mediterranean, or the Persian Gulf. Accordingly, the oldest map of the world which has been found is one accompanying a cuneiform inscription, and representing the plain of Mesopotamia with the Euphrates flowing through it, and the whole surrounded by two concentric circles, which are named briny waters. Outside these, however, are seven detached islets, possibly representing the seven zones or climates into which the world was divided according to the ideas of the Babylonians, though afterwards they resorted to the ordinary four cardinal points. What was roughly true of Babylonia did not in any way answer to the geographical position of Greece, and it is therefore probable that in the first place they obtained their ideas of the surrounding ocean from the Babylonians.
It was after the period of Homer and Hesiod that the first great expansion of Greek knowledge about the world began, through the extensive colonisation which was carried on by the Greeks around the Eastern Mediterranean. Even to this day the natives of the southern part of Italy speak a Greek dialect, owing to the wide extent of Greek colonies in that country, which used to be called "Magna Grecia," or "Great Greece." Marseilles was also one of the Greek colonies (600 B.C.), which, in its turn, sent out other colonies along the Gulf of Lyons. In the East, too, Greek cities were dotted along the coast of the Black Sea, one of which, Byzantium, was destined to be of world-
