In Greece, the circle in the north shows Thessalian Achaea, and the oval the district of Achaea in Peloponnesus. Ionia is indicated in Asia Minor (enlarge)

Achaea has been called a region in southern Thessaly, and also the northern coast of the Peloponnesus. Those who marched against Troy were called Achaeans, and sometimes Argives for living in Argolis. The Achaeans came originally from Thessaly, in mainland Greece, and settled in Argos and Lacedaemon (southern Peloponnesus). Having mingled with the Danaans (those ruled by Danaus ₁ and his descendants) they lived there until the return of the HERACLIDES. The mingling of Achaeans and Danaans is described through the marriages of two sons of Achaeus ₁ (from whom the Achaeans derive their name) with two daughters of Danaus ₁, the man who is otherwise known as father of the DANAIDS.

Thessalian and Peloponnesian Achaea

Thessalian Achaea is the land later known by the names of Phthiotis and Hellas. Both that territory and Peloponnesian Achaea own their names to Achaeus ₁, son of Xuthus ₁, brother of Aeolus ₁ and son of Hellen ₁, son of Deucalion ₁, the man who survived the Flood. It is also told, however, that Achaea was named after Achaeus ₂, son of Poseidon and Larisa ₁, the woman after whom the citadel of Argos and two cities in Thessaly were named. Peloponnesian Achaea is the narrow strip of land extending along the Gulf of Corinth, bordering Arcadia on the south and Elis on the southwest.

First ruler in the region

The first to rule this region was Aegialeus ₂, son of the river god Inachus and the Oceanid Melia. He became king in the adjacent district of Sicyonia, founding a city and calling the land Aegialus after himself.

Xuthus ₁ expelled twice

In the meantime, Xuthus ₁ was being expelled from Thessaly by his brothers. He first settled in Athens, where he married Creusa ₁, daughter of King Erechtheus. When the king died, Xuthus ₁, who by then had become influential in Athens, was asked to decide who among the sons of Erechtheus should succeed him in the throne. Xuthus ₁ then appointed Cecrops ₂ as the successor of Erechtheus, and thereby he won the enmity of the other sons of Erechtheus, who banished him from the city. Xuthus ₁ then came as an exile to Aegialus, where he made his home and died. Xuthus ₁'s son Achaeus ₁ gathered troops from both Aegialus and Athens and with them he campaigned against the southern Thessalians, recovering his father's rights and becoming king in Phthiotis (the region in southern Thessaly).

Ion ₁ inherits Peloponnesian Achaea

Xuthus ₁'s other son Ion ₁ waged instead war against King Selinus, who had inherited and enlarged the kingdom of Aegialeus ₂. As this war was taking place, Selinus offered Ion ₁ his daughter Helice ₂, proposing to adopt him as son and successor. Ion ₁ accepted this proposal, married Helice ₂, and having later inherited Selinus' throne, founded a city Helice and called the inhabitants of his realm Ionians. When war between Athens and Eleusis broke up, Ion ₁ was invited by the Athenians to be their leader in the war, dying in the battlefield. His descendants continued to rule the territory (Achaea) and were called Ionians. But then Achaeans were called those who lived in Argolis. For the sons of Achaeus ₁—Architeles ₁ and Archander—came to Argos and married the daughters of Danaus ₁, Automate and Scaea. And as they and their descendants came to rule cities both in Argos and Lacedaemon, the inhabitants were named Achaeans because of their common ancestor Achaeus ₁. However, when after the Trojan War the HERACLIDES invaded the Peloponnesus—claiming that their rulers, being descended from Pelops ₁, were usurpers—the Achaeans were forced to leave Argolis. By then the ruler of both Argives and Achaeans was Tisamenus ₂, who inherited the throne of Orestes ₂, son Agamemnon, son of Atreus, son of Pelops ₁. Not being able to resist the attack of the HERACLIDES, Tisamenus ₂ sent heralds to the Ionians asking for permission to settle among them without warfare. The Ionians, however, rejected his proposal, fearing that Tisamenus ₂, because of his lineage and power, would become their king. For that reason, a war broke up between the Achaeans, led by Tisamenus ₂, and the Ionians. The latter were defeated, but Tisamenus ₂ was killed in battle, though others say that he was killed on another occasion by the HERACLIDES. This is how the Achaeans settled in Achaea, and the Ionians, having been expelled from their country, were forced to emigrate, coming first to Attica, where King Melanthus ₁ of Athens allowed them to settle.

The Ionians after losing their land

Now Melanthus ₁ (son of Andropompus ₁, son of Borus ₃, son of Penthilus ₂, son of Periclymenus ₁, son of Neleus), had himself, in these times of convulsion, been expelled from Messenia by the HERACLIDES Temenus ₂ and Cresphontes. He then came to Athens and deposed King Thymoetes ₂ (son of Oxyntes), who is said to have been the last of the Athenian kings descended from Theseus. Having thus conquered a new kingdom, Melanthus ₁ allowed the Ionians to settle in Attica, hoping that their presence would strenghthen Athens' defences against the HERACLIDES. But others have said that this was not the only reason, for there had always been goodwill between the Athenians and the Ionians, on account of the help the former received from Ion ₁ in the war Athens fought against Eleusis. Melanthus ₁ was succeeded as king of Athens by his son Codrus ₁, and while the latter was king, the HERACLIDES did attack Athens as Melanthus ₁ had feared. However, they accomplished nothing, except that Codrus ₁ was killed in battle. After the king's death, his sons quarrelled for the throne and the dispute had to be settled by the oracle of Delphi, which appointed Medon ₁₁ as king.
When the throne succession was decided, Neileus and the other sons of Codrus ₁ set out to found a colony in Asia Minor, taking with them anyone who wished to go. But the majority of the emigrants were the Ionians who had settled in Attica during the rule of Melanthus ₁, and they left Athens under Messenian leadership (for that was the origin of Melanthus ₁₎. In this way the Ionians came to Caria in Asia Minor, and led by the sons of Codrus ₁, founded some cities and conquered others (see Ionia).