Greek mythology gives Hermione's founding to the Dryopes, a people who appear in several ancient sources but who have never been easy to locate with precision on any map of the ancient world. According to tradition, Heracles drove them from their original territory around Mount Oeta in central Greece, and they dispersed south into the Peloponnese, establishing three principal towns: Hermione, Asine, and Eïon. The Dorians eventually conquered Asine and Eïon, but Hermione survived as an independent Dryopian state for centuries longer. It was prominent enough to be listed first among the cities of the Amphictyony — the religious confederation whose members met on the nearby island of Calaureia — and the sources are explicit that Hydra, the island clearly visible from Hermione's shore, once belonged to the Hermionians, who later surrendered it to Samian pirates, who in turn gave it over to the Troezenians.

The Hermionitic Gulf is the body of water between the southern Argolic coast and the island of Hydra. Ancient geographers were careful to distinguish it from both the Argolic Gulf to the north and the Saronic Gulf to the east — it had its own identity, its own name, derived from the city on its northern shore. That geographic specificity tells you something about how Hermione was regarded in antiquity: it was not an appendage of Argos or a dependency of Sparta but a place with its own territorial gravity, a city that gave its name to a sea. The Greek traveller Pausanias, writing in the second century, describes the old city as occupying a promontory seven stadia long and three stadia broad at its widest point, with a harbour on each side. By his time, the original lower city was already abandoned. The population had moved uphill.

Pausanias catalogued what he saw at Hermione with his usual thoroughness, and what he found was remarkable. The most important temple was the sanctuary of Demeter Chthonia — Demeter of the Earth Below — a Dryopian cult that persisted even after Argives displaced the original population. Cilician pirates plundered the sanctuary at some point, but it endured. Opposite the temple of Demeter Chthonia stood a temple to Clymenus, and beside it was the stoa of Echo, an arcade whose construction caused sounds to repeat three times. Nearby, three sacred enclosures surrounded by stone walls held sanctuaries of Clymenus, Hades, and the Acherusian Lake — the mythological river of the underworld. Within the sanctuary of Clymenus, Pausanias reports, there was an opening in the earth. The Hermionians believed it was the shortest road to Hades. This conviction had a practical consequence: they did not put coins in their dead people's mouths, sparing them the ferry fare that other Greeks considered obligatory.

Hermione's political history followed the erratic rhythms of the ancient Greek world. The Hermionians sent three ships to Salamis in 480 BC and 300 soldiers to Plataea in 479 BC, contributing to the defeat of the Persian invasion on a scale appropriate to a small but independent city-state. Around 464 BC, the Argives took possession of the city — peacefully, Pausanias supposes, perhaps at the same time they subdued Mycenae and Tiryns. Some expelled Hermionians resettled at Halieis. The city became Doric but retained its old Dryopian religious practices, particularly the cult of Demeter Chthonia. Around 230 BC, a tyrant named Xenon ruled the city. When Aratus of Sicyon liberated Argos and captured the Acrocorinthus, Xenon read the political situation clearly and stepped down voluntarily in 228 BC — making him, according to ancient accounts, the last tyrant in the Peloponnese to surrender his power. Hermione then joined the Achaean League and continued to mint coins and produce inscriptions for centuries afterward.

Systematic archaeological investigation of Hermione began only in 2015, when Greek and Swedish archaeologists launched a joint programme called A Greek Cityscape and Its People, continued since 2018 as Hermione: A Model City. The project uses integrated methods — architectural survey, landscape analysis, study of funerary practices and family structures — to reconstruct what life looked like in a Greek polis over the long term. The site is not a dramatic ruin in the manner of Mycenae or Corinth; the modern village of Ermioni covers much of it, and the layers are subtle. Results have appeared in Opuscula, the journal of the Swedish Institute at Athens. What is emerging is the portrait of a city that kept its own identity through successive waves of conquest and cultural change, outlasting many of its more famous neighbours by holding to its promontory, its harbours, and its singular conviction that the underworld was, if you knew where to look, right there beneath your feet.