It is a probable opinion of scholars, that the halting-place of the Hellenes, whence, in successive waves, they passed over into Greece, was _Phrygia,_ in the north-west of Asia Minor. Preceding the Greeks both in northern Greece and in Peloponnesus, and spread over the coasts and islands of the Archipelago, was a people of whom they had an indistinct knowledge, whom they called _Pelasgians._ They were husbandmen or herdsmen. Their national sanctuary was at _Dodona,_ in Epirus. The "Cyclopean" ruins, composed of huge polygonal blocks of stone, which they left behind in various places, are the remnant of their walls and fortifications. The Greeks looked back on these Pelasgian predecessors as different from themselves. Yet no reminiscences existed of any hostility towards them. It is plausibly conjectured that this prehistoric people were emigrants from the region of Phrygia at a more ancient date, and that the Hellenes, a more energetic and gifted branch of the same stock, followed them, and, without force or conflict, became the founders and leaders of a new historic movement, in which the Pelasgians disappeared from view. In this second migration, the ancestors of the _Ionians_ went down from Phrygia to the coast of Asia Minor, and began the career which made them a maritime and commercial people. The _Dorians_ crossed over to the highlands of northern Greece, where they became hardy mountaineers, not addicted to the sea. The one tribe were to be eventually the founders of _Athens_; the other, of _Sparta_. Besides these two main tribes, the _Aeolians_ occupied Thessaly, Boeotia, Aetolia, and other districts. To them the _Achaeans_, who were supreme in Peloponnesus in the days of Homer, were allied.