Both Sparta and Megalopolis sent embassies to Athens.
The foundation of the new federal capital Megalopolis threw Tegea somewhat into the shade.
Traces remain of paved roads both within the agora and leading out of it; but the whole site is now a deserted and feverish swamp. The site is interesting for comparison with Megalopolis; the nature of its plan seems to imply that its main features must survive from the earlier "synoecism" a century before the time of Epaminondas.
But Aratus, whose jealousy could not brook to see a Spartan at the head of the Achaean league called in Antigonus Doson of Macedonia, and Cleomenes, after conducting successful expeditions to Megalopolis and Argos, was finally defeated at Sellasia, to the north of Sparta, in 222 or 221 B.C. He took refuge at Alexandria with Ptolemy Euergetes, but was arrested by his successor, Ptolemy Philopator, on a charge of conspiracy.
In the following campaign of 362 Mantineia, after narrowly escaping capture by the Theban general Epaminondas, became the scene of a decisive conflict in which the latter achieved Achaeans and jealousy of Megalopolis, was punished in 222 by a thorough devastation of the city, which was now reconstituted as a dependency of Argos and renamed Antigoneia.