Archelaus' son Teleclus is said to have taken Amyclae, Pharis and Geronthrae, thus mastering the central Laconian plain and the eastern plateau which lies between the Eurotas and Mt Parnon: his son, Alcamenes, by the subjugation of Helos brought the lower Eurotas plain under Spartan rule.
The word was derived in antiquity from the town of Helos in Laconia, but is more probably connected with 'Aos, a fen, or with the root of AEiv, to capture.
Pausanias, however (following Sosibius), interprets a long series of conflicts in Arcadia as stages in a gradual advance southward, ending with the conquest of Amyclae by King Teleclus (c. 800 B.C.) and of Helos by King Alcamenes (c. 770 B.C.).
The most important towns, besides Sparta and Gythium, were Bryseae, Amyclae and Pharis in the Eurotas plain, Pellana and Belbina on the upper Eurotas, Sellasia on the Oenus, Caryae on the Arcadian frontier, Prasiae, Zarax and Epidaurus Limera on the east coast, Geronthrae on the slopes of Parnon, Boeae, Asopus, Helos, Las and Teuthrone on the Laconian Gulf, and Hippola, Messa and Oetylus on the Messenian Gulf.