With a territory more extensive than any other region of Peloponnesus, peopled by a hardy race, proud of its ancient origin and immemorial possession of the land, and of its peculiar religious traditions, Arcadia—the Greek Switzerland—had never possessed any weight in the affairs of the nation; the land only served as a thoroughfare for hostile armies, and sent forth its sons to recruit the forces of foreign powers—Greek or barbarian—and to shed their blood in quarrels in which they had no concern. The battle of Leuctra opened a prospect of carrying it into effect. A Mantinean named Lycomedes, a man of large fortune and of the highest birth in his native city, seems to have been either the author or the most active mover of the project which was now formed, and which was at least partly executed in the course of the same year (371). The object was to unite the Arcadian people in one body, yet so as not to destroy the independence of the particular states; and with this view it was proposed to found a metropolis, to institute a national council which should be invested with supreme authority in foreign affairs, particularly with regard to peace and war, and to establish a military force for the protection of the public safety. And though there is no reason to doubt that Lycomedes and those who shared his views were chiefly desirous of rescuing their country from a degrading subjection to her imperious neighbour, and of elevating her to an honourable station among the Greek commonwealths, they undoubtedly did not overlook the accession of strength which would result from this event to their party, in its contest with its domestic adversaries. Their plan could not fail to be agreeable to the Thebans, just in proportion as it was alarming to Sparta; and it was very early communicated to Epaminondas. Within a few months after the battle of Leuctra, a meeting of Arcadians from all the principal towns was held, to deliberate on the measure; and under its decree a body of colonists, collected from various quarters, proceeded to found a new city, which was to be the seat of the general government, and was called Megalepolis, or Megalopolis (the Great City).
The city was designed on a very large scale, and the magnitude of the public buildings corresponded to its extent; the theatre was the most spacious in Greece. The population was to be drawn from a great number of the most ancient Arcadian towns. Pausanias gives a list of forty which were required to contribute to it. The greater part of them appear to have been entirely deserted by their inhabitants; others retained a remnant of their population, but in the condition of villages subject to Megalopolis. Trapezus made an obstinate resistance; and its citizens who survived the struggle preferred quitting their native land to changing their abode in it, and having found means for embarking for the Euxine, were hospitably received as kinsmen in the city of the same name. Lycosura—which boasted of being the most ancient city under the sun—was spared out of respect for the sanctity of one of its temples. The districts which were thus drained of their population never recovered it, and were left in a great measure uncultivated.
The most interesting subject connected with this event, the constitution under which Arcadia was to be united, is unfortunately involved in the greatest obscurity. Megalopolis was the place appointed for the deliberation of the supreme council of the Arcadian body. But of this council we only know that it was commonly described by the name of the Ten Thousand—an appellation which raises a number of perplexing questions. For that it was a representative assembly, and was not intended to consist only of Megalopolitans, is clear both from the terms in which it is spoken of, and from the nature of the case: this would have been a privilege which the other cities would never have conceded to a colony formed out of the most insignificant townships. On the other hand, that so numerous a body should have been collected, either at stated times or as often as occasion required, from the other parts of Arcadia, is scarcely less hard to understand.