Contemporaneously with the accession of Peisistratus, this state of things becomes altered both in and out of Hellas,—the former as a consequence of the latter: for at that time begins the formation of the great Persian empire, which absorbs into itself not only Upper Asia and Asia Minor, but also Phenicia, Egypt, Thrace, Macedonia, and a considerable number of the Grecian cities themselves; and the common danger, threatening the greater states of Greece proper from this vast aggregate, drives them, in spite of great reluctance and jealousy, into active union. Hence arises a new impulse, counterworking the natural tendency to political isolation in the Hellenic cities, and centralizing their proceedings to a certain extent for the two centuries succeeding 560 B. C.; Athens and Sparta both availing themselves of the centralizing tendencies which had grown out of the Persian war. But during the interval between 776-560 B. C., no such tendency can be traced even in commencement, nor any constraining force calculated to bring it about. Even Thucydidês, as we may see by his excellent preface, knew of nothing during these two centuries except separate city-politics and occasional wars between neighbors: the only event, according to him, in which any considerable number of Grecian cities were jointly concerned, was the war between Chalkis and Eretria, the date of which we do not know. In this war, several cities took part as allies; Samos, among others, with Eretria,—Milêtus with Chalkis:[101] how far the alliances of either may have extended, we have no evidence to inform us, but the presumption is that no great number of Grecian cities was comprehended in them. Such as it was, however, this war between Chalkis and Eretria was the nearest approach, and the only approach, to a Pan-Hellenic proceeding which Thucydidês indicates between the Trojan and the Persian wars. Both he and Herodotus present this early period only by way of preface and contrast to that which follows,—when the Pan-Hellenic spirit and tendencies, though never at any time predominant, yet counted for a powerful element in history, and sensibly modified the universal instinct of city-isolation. They tell us little about it, either because they could find no trustworthy informants, or because there was nothing in it to captivate the imagination in the same manner as the Persian or the Peloponnesian wars. From whatever cause their silence arises, it is deeply to be regretted, since the phenomena of the two centuries from 776-560 B. C., though not susceptible of any central grouping, must have presented the most instructive matter for study, had they been preserved. In no period of history have there ever been formed a greater number of new political communities, under such variety of circumstances, personal as well as local. And a few chronicles, however destitute of philosophy, reporting the exact march of some of these colonies from their commencement,—amidst all the difficulties