MANTINEIA, or MANTINEA  , an ancient city of Arcadia, Greece, situated in the long narrow plain running north and south, which is now called after the chief town Tripolitsa . Tegea was in the same valley, about so m . S. of Mantineia, and the two cities continually disputed the supremacy of the district . In every great war we find them ranged on opposite sides, except when superior force constrained both . The worship and mysteries of Cora at Mantineia were famous . The valley in which the city lies has no opening to the coast, and the water finds its way, often only with much care and artificial aid, through underground passages (katavothra) to the sea . It is bounded on the west by Mount Maenalus, on the east by Mount Artemision . Mantineia is mentioned in the Homeric catalogue of ships, but in early Greek times existed only as a cluster of villages inhabited by a purely agricultural community . In the 6th century it was still insignificant as compared with the neighbouring city of Tegea, and submitted more readily to Spartan overlordship . The political history of Mantineia begins soon after the Persian wars, when its five constituent villages, at the suggestion of Argos, were merged into one city, whose military strength forthwith secured it a leading position in the Peloponnesus . Its policy was henceforth guided by three main considerations . Its democratic constitution, which seems to have been entirely congenial to the population of small freeholders, and its ambition to gain control over the Alpheus watershed and both the Arcadian high roads to the isthmus, frequently estranged Mantineia from Sparta and threw it into the arms of Argos .

But the chronic frontier disputes with Tegea, which turned the two cities into

bitter enemies, contributed most of all to determine their several a notable victory but lost his own life . After the withdrawal of the Thebans from Arcadia Mantineia failed to recover its pre-eminence from Megalopolis, with which city it had frequent disputes . In contrast with the Macedonian sympathies of Megalopolis Mantineia joined the leagues against Antipater (322) and Antigonus Gonatas (266) . A change of constitution, imposed perhaps by the Macedonians, was nullified (about 250) by a revolution through which democracy was restored . About 235 B.C . Mantineia entered the Achaean League, from which it had obtained protection against Spartan encroachments, but soon passed in turn to the Aetolians and to Cleomenes III. of Sparta .