Cleonae stood in a small plain upon a river flowing into the Corinthian Gulf a little westward of Lechaeum.
It derived its chief importance from the Nemean Games being celebrated in its territory, in the grove of Nemea, between Cleonae and Phlius.
[8] It was conquered by the Dorians, whereupon some of its inhabitants, together with those of the neighbouring town of Phlius, are said to have founded Clazomenae in Asia Minor.
[9] In the Dorian conquest, Cleonae formed part of the lot of Temenus, and in early times was one of the confederated allies or subordinates of Argos.
After the Greco-Persian Wars, the Cleonaeans assisted the Argives in subduing Mycenae;[10] and they fought as the allies of Argos at the Battle of Mantinea (418 BCE).