History of the Peloponnesian War

The same summer also, the Athenians made Nymphodorus the son of Pythos, of the city of Abdera (whose sister was married to Sitalces and that was of great power with him), their host, though before they took him for an enemy, and sent for him to Athens, hoping by his means to bring Sitalces the son of Teres, king of Thrace, into their league.

This Teres, the father of Sitalces, was the first that advanced the kingdom of the Odrysians above the power of the rest of Thrace.

For much of Thrace consisteth of free states. And Tereus that took to wife out of Athens Procne the daughter of Pandion was no kin to this Teres nor of the same part of Thrace. But that Tereus was of the city of Daulia in the country now called Phocis, then inhabited by the Thracians. And the fact of the women concerning Itys was done there; and by the poets, where they mention the nightingale, that bird is also called Daulias. And it is more likely that Pandion matched his daughter to this man, for vicinity and mutual succour, than with the other that was so many days' journey off as Odrysae. And Teres (which is also another name) was the first that seized on the kingdom of Odrysae.

Now Sitalces, this man's son, the Athenians got into their league that they might have the towns lying on Thrace and Perdiccas to be of their party.

Nymphodorus, when he came to Athens, made this league between them and Sitalces and caused Sadocus the son of Sitalces to be made free of Athens and also undertook to end the war in Thrace. For he would persuade Sitalces to send unto the Athenians a Thracian army of horsemen and targeteers.

He likewise reconciled Perdiccas to the Athenians, and procured of him the restitution of Therme. And Perdiccas presently aided the Athenians and Phormio in the war against the Chalcideans.

Thus were Sitalces the son of Teres, king of Thrace, and Perdiccas the son of Alexander, king of Macedonia, made confederates with the Athenians.