History of the Peloponnesian War

But many generations after, being fallen into misery, they communicated their city with the Ambraciotes, bordering upon Amphilochia; and then they first learned the Greek language now used from the Ambraciotes that lived among them.

For the rest of the Amphilochians were barbarians.

Now the Ambraciotes in process of time drave out the Argives and held the city by themselves. Whereupon the Amphilochians submitted themselves to the Acarnanians, and both together called in the Athenians who sent thirty galleys to their aid and Phormio for general. Phormio, being arrived, took Argos by assault and, making slaves of the Ambraciotes, put the town into the joint possessions of the Amphilochians and Acarnanians.

And this was the beginning of the league between the Athenians and Acarnanians.