the Mediterranean, whether they were Achaeans, Celts, Goths, Norsemen or Turks, must be in part accounted for by the mere fact that they formed in each case the upper and ruling class, and could therefore afford to lead a life of luxury which was the very bane of their race.’ For our part we are convinced with Leaf[7] that ‘an invasion of Southern Greece by rude tribes from the north or north-west swept away the Achaean civilisation after the Homeric age’; that a military confederation of hereditary monarchs and nobles, such as that of the Achaeans, could not have lost its unified control if these inherent factors of disintegration had not been supplemented by an invasion from without. O. Müller[8] has pointed out that in Thessaly, the former realm of Peleus and Achilles, there existed in historical times three strata of social and political privilege: (1) the Thessalians, post-Homeric immigrants, who ruled directly over the central territory, including the towns of Larissa, Crannon, Pharsalus, Iolcus. (2) Perioeci or semi-independent vassals, such as the Perrhaebians, the Magnesians, and the Phthiotian Achaeans, who paid tribute and were bound to assist in war. (3) Penestae, of Pelasgian stock, like the Helots of Sparta, who cultivated the land and served in war, who had private rights but no political privileges, who were, in a word, serfs, but not slaves. He mentions, further,[9] that the Achaeans of the north coast of the Peloponnese remained in towns and fortified strongholds, keeping entirely aloof from the natives; they were still conquerors here, though they had become vassals elsewhere. In Sparta there appears to have been a mingling of Achaeans and Dorians. Thucydides says[10] that here ‘the few rule over the many, having obtained sovereignty by victory in the field.’ That this victory was not very decisive is suggested by the view, which is commonly held,[11] that one of the two Royal families of Sparta was Achaean. The Perioeci of Laconia were always considered Achaeans[12]; there were about a hundred towns of Laconian Perioeci, both inland and on the coast; they paid tribute to Sparta, but they had a monopoly of trade and commerce, and in the time of Nabis were liberated and federated as independent states of the Achaean league.[13] The Helots, of course, were serfs. They tilled the soil, and lived in hamlets which made up the greater part of the town of Sparta. They were probably Pelasgians, though they are called Achaeans by Theopompus.[14] Similarly, in Argos and in Corinth there are traces of pre-Dorian peoples who can probably be regarded as including some remnants of the Homeric Achaeans.[15]