The Achaeans (in Greek Αχαιοί, Akhaioi) is one of the collective names used for the Greeks in Homer's Iliad (used 598 times) and Odyssey. The other names are the Danaans (Δαναοί, used 138 times in the Iliad) and Argives (Αργείοι, used 29 times in the Iliad). In the historical period, the Achaeans were the inhabitants of the region of Achaea, a region in the north central part of the Peloponnese. The city states of this region formed a confederation known as the Achaean League which was influential during the 3rd and 2nd centuries BC.
The Achaeans are one of the four main tribes occupying the ancient Greek mainland (Achaeans, Aeolians, Ionians, Dorians). The name Achaeans came to mean all the Greeks at the time of the Trojan War. 
The Homeric "long-haired Achaeans" would have been a part of the Mycenaean civilization that dominated Greece from ca. 1600 BC, with a history as a tribe that may have gone back to the prehistoric Hellenic immigration in the late 3rd millennium BC. It has been suggested that the Achaeans had not settled in the Greek mainland until the Dorian invasions of the 12th century BC. It is possible that Homer's Achaean leaders held power in the Mycenean world but were replaced by the Dorians. Herodotus identified the Achaeans of the northern Peloponnese as descendants of these earlier Achaeans.
A scholarly consensus has not yet been reached on the origin of the historic Achaeans, and is still hotly debated. Former emphasis on presumed race, in which John A. Scott could write an article on Achaean blondness, compared to the dark locks of "Mediterranean" Poseidon, on the basis of hints in Homer, has been laid aside. The contrasting view that "Achaeans", as understood through Homer, are "a name without a country", an ethnos created in the Epic tradition, has modern supporters among those who conclude that "Achaeans" were redefined in the fifth century, as contemporary speakers of Aeolic Greek. Professor Karl Beloch has suggested that there was no Dorian invasion, but rather that the Peloponnesian Dorians were the Achaeans. Professor Eduard Meyer, disagreeing with Beloch, has instead put forth the suggestion that the real-life Achaeans were mainland pre-Dorian Greeks. His conclusion is based on his research on the similarity between the languages of the Achaeans and pre-historic Arcadians. And Professor William Prentice disagrees with both, noting that archeological evidence suggests that the Achaeans instead migrated from “southern Asia Minor to Greece, probably settling first in lower Thessaly” probably prior to 2000 BC.
Some Hittite texts mention a nation lying to the west called Ahhiyawa. An important example is the Tawagalawa Letter written by an unnamed Hittite king of the empire period (14th century B.C.) to the king of Ahhiyawa, treating him as an equal and suggesting that Miletus (Millawanda) was under his control. It also refers to an earlier "Wilusa episode" involving hostility on the part of Ahhiyawa. In the earliest reference to this land, in a letter outlining the treaty violations of the Hittite vassal Madduwatta, it is called Ahhiya. Ahhiya(wa) has been identified with the Achaeans of the Trojan War and the city of Wilusa with the legendary city of Troy (note the similarity with Ίλιον, (w)Ilion, the name of the acropolis of Troy). However the exact relationship of the term Ahhiyawa to the Achaeans beyond a similarity in pronunciation is hotly debated by scholars, even following the discovery that Mycenaean Linear B is an early form of Greek; the earlier debate was summed up in 1984 by Hans G. Güterbock of the Oriental Institute.
During the 5th year of Pharaoh Merneptah, a confederation of Libyan and northern peoples is supposed to have attacked the Western Delta. Included amongst the ethnic names of the repulsed invaders is the Ekwesh or Eqwesh, whom some have seen as Achaeans. Homer mentions an Achaean attack upon the delta, and Odysseus speaks of the same when he talks to the shade of Menelaus. Later Greek myths also say that Helen had spent the time of the Trojan War in Egypt, and not at Troy, and that after Troy the Greeks went there to recover her. There is also the strange myth of the brothers Aegyptus and Danaus, sons of Belus, with the latter supposedly coming from Egypt, that Marianne Luban has suggested may date to this time.
The same Egyptian sources indicate that Merneptah defeated the invasion, killing 6,000 soldiers and taking 9,000 prisoners. To be sure of the numbers, among other things, he took the penises of all uncircumcised enemy dead and the hands of all the circumcised, from which history learns that the Ekwesh were circumcised, a fact causing some to doubt they were Greek.
In Greek mythology
In Greek mythology the perceived cultural divisions among the Hellenes were represented as legendary lines of descent that identified kinship groups, among them the Achaeans. The Greek ethnoi were named in their honor Achaeans, Danaans, Kadmeioi, Hellenes, Aeolians, Ionians, Dorians. Kadmos and Danaos came from Egypt, and Pelops from Phrygia settled in mainland Greece and were assimilated and Hellenized. Hellen, Graicos, Magnis, and Macedon were sons of Deucalion and Pyrrha, the only people who survived the Great Flood; the ethne were said to have originally been named after the elder son Graikoi but renamed later after Hellen who was proved to be the strongest. Sons of Hellen and the nymph Orsiis were Dorus, Xuthos, and Aeolus. Sons of Xuthos and Kreousa, daughter of Erechthea, were Ion and Achaeus.
- Aegean civilization
- Mycenaean Greece
- Historicity of the Iliad
- Mycenaean language
- The Achaean League was a confederation of Greek city states in Achaea, a territory on the northern coast of the Peloponnese. An initial confederation existed during the 5th through the 4th century BC.
- Scott, "The Complexion of the Achaeans" The Classical Journal.20..6 (March 1925:366-367)
- As William K. Prentice expressed this long-standing skepticism of a genuine Achaean ethnicity in the distant past, at the outset of his article "The Achaeans", American Journal of Archaeology 33.2 (April 1929:206-218) p 206
- K. J. Beloch, Griechische Geschichte, 1: I, p. 92, and p. 88, n. 1.
- Eduard Meyer, Geschichte rles Alterturns, 112, I (1928), p. 251
- Prentice 1929:206-218.
- Translation of the Tawagalawa Letter
- Translation of the Sins of Madduwatta
- Hans G. Güterbock, "Hittites and Akhaeans: A New Look" Proceedings of the American Philosophical Society 128.2 (June 1984), pp. 114-122. Bibliography.
- Encyclopaedia Britannica 1911: "Achaeans"
- Sites and Photos: Mediterranean and Classical Archaeology Images
- Detailed cultural studies of Minoan Crete and relations with the mainland "Mycenean" tribes of Achaians
- The Greek Age of Bronze weapons and warfare
- Tsotakou-Karveli. Lexicon of Greek Mythology. Athens: Sokoli, 1990.