Every ancient Greek city wanted a founder worth boasting about, and Erythrae claimed two. The traveler Pausanias recorded that Erythrus, a son of the Cretan judge Rhadamanthus, arrived first with a mixed band of Cretans, Carians, and Lycians. Later came Knopos, son of the Athenian king Codrus, leading an Ionian colony, which is why the place was sometimes called Cnopopolis. The city sat a little inland from the Bay of Erythrae, balanced between two mountains, Mimas and Corycus, with its working harbor down on the coast at a spot the Romans knew as Cissus. From those slopes came excellent wine, hardy goats, good timber, and the millstones that gave Erythrae a modest fame across the Aegean. It was a place that made useful things and minded the sea.

Erythrae's true claim to immortality was the Sibyl. The Apollonian oracle here was served by a line of prophetesses, the most renowned of them named Herophile, who was said to have foretold the Trojan War, warning the Greeks that Troy would fall and that Homer would later write falsehoods about it. A second seer, Athenais, lived in the age of Alexander the Great. The Erythraean Sibyl took her place among the most quoted oracles of antiquity, and the story of her leaves, lettered so their first characters spelled out hidden words, fascinated readers for centuries. When Alexander returned to Egypt in 331 BC, envoys reported that the long-silent oracles at Erythrae and nearby Didyma had suddenly spoken, declaring him the son of Zeus. Whatever the gods intended, the timing suited a young king already certain of his own divinity.

Erythrae spent its classical centuries as a small power forever choosing sides. It sent only eight ships to the Battle of Lade, a reminder of its modest scale, and bowed for a long while to Athenian supremacy. Around 453 BC it refused to pay tribute and bolted from the Delian League, only to be hauled back by an Athenian garrison and a new government. It revolted again in 412 BC alongside Chios and Clazomenae, then drifted between Athens and Persia as the winds of the Peloponnesian War shifted. The city courted powerful neighbors too, honoring the Carian ruler Mausolus as a benefactor and signing a mutual-defense treaty with Hermias, the tyrant of Atarneus. In 334 BC Alexander restored its freedom, and the city flourished anew.

Rome inherited Erythrae after King Attalos III of Pergamon willed his kingdom to the republic in 133 BC, and the city enjoyed a stretch as a free city of the province of Asia, prized for wine and prophecy alike. Earthquakes in the first century AD broke its momentum, but bishops are recorded here from 431 well into the thirteenth century, and a minor Byzantine governor held the town in the ninth and tenth. From the 1700s into the early 1900s the port, then called Litri, traded busily with Chios and Smyrna. Today the archaeological site rests within Ildırı, partly excavated between 1969 and 1979 by the Turkish scholar Ekrem Akurgal and then left mostly to the goats. The well-preserved walls and their towers still stand, a theatre is carved into the acropolis slope, and the bay glitters below exactly as it did when the Sibyl read her scattered leaves.