It is well-known that a primary Greek distinction was that between Hellene and barbarian, and it is equally familiar that the distinction had not been fully formed in the time of Homer. There is no indication that the Trojans were felt to be fundamentally different from the Acheans, although it is likely enough that the allies who attacked the great city of the Troad were of different descent from those that defended it. The one instance found in Homer of the word βάρβαρος is in the compound βαρβαρόφωνος, “of barbarous speech” (Iliad ii. 867), which makes the original meaning of the word apparent. A Greek was one whose speech was intelligible. All others were barbarians, “jabberers.” And it is not only incidentally that Homer fails to make the racial division clear. When he of set purpose contrasts the two armies, as in Iliad iv. 422-437, it is the contrast between the silent discipline of the Greeks and the loose, noisy marshaling of the Trojans: “For all were not of one speech or of a single language. Mixed were their tongues, since the men came from far-off lands.” It is probably in the course of just such expeditions as the Iliad tells of, a joint movement against a common foe, that a sense of national unity arose, and it is likely that it came to include many tribes of different race. We do not know what real basis there is for the traditional divisions of Ionians, Dorians, and Aeolians. These divisions have not proved very valuable means of classification to modern students of Greek dialects. The generic name of Greek to the East was Yavan, obviously the same as Ionian,[46] and that name indicates where the first contact took place. The struggles of Greeks to establish themselves on the coast of Asia Minor probably created the three traditional groups, by forcing them to combine against threatened destruction. But there is nothing to show that any real feeling of common origin and common responsibility existed even here. On the continent, again, there were large groups of men whom the Greeks found difficulty in classifying. There were some Epirotes and Macedonians whose claim to be Greeks was admitted. On the whole, however, Epirotes and Macedonians were classed as barbarians, though a different sort of barbarians from Scythian and Phrygian. The first realization of national unity came with the first great national danger, the catastrophe that impended from the Persians.