The Achaeans (in ancient Greek Akhaioí) were one of the first Indo-European peoples to invade Greece in the 2nd millennium BC. BC, driving out the first inhabitants, the Pelasgians thanks to their military supremacy (use of the sword instead of the dagger, use of bronze).
Argolis becomes their stronghold from where they dominate the rest of Greece. Homer thus speaks of “Achaeans” or “Argians” to designate all the Greeks gathered before Troy. Their main centers are the cities of Argos, Tiryns, Pylos but especially Mycenae, hence the name Mycenaean civilization for the period from the 17th to the 12th century BC. approximately. The fall of Achaean rule is traditionally attributed to the Dorian invasion, but it is now believed that the great invasion was rather a series of small incursions, spaced out in time.
Their eponymous ancestor is Achaïos, son of Xouthos and Creüse, half-brother of Ion (eponymous ancestor of the Ionians).
According to some scholars, the Hittite term Ahhiyawa mentioned in chronicles referred to the Achaeans of the Homeric tradition.
In the North-West of Argolis, a mountainous region called "Achaea", also holds to have sheltered a flourishing development of the Achaean civilization in cities like Sicyon, Patras, Erymanthe and further south, Elis and Olympia.