Funke, Peter, and Nino Luraghi, eds. 2009. The Politics of Ethnicity and the Crisis of the Peloponnesian League. Hellenic Studies Series 32. Washington, DC: Center for Hellenic Studies. http://nrs.harvard.edu/urn-3:hul.ebook:CHS_FunkeP_LuraghiN_eds.The_Politics_of_Ethnicity.2009.
II. Achaea and the Peloponnese in the Late Fifth-Early Fourth Centuries
- The political procedure of the Achaeans shows that by this time there was a sort of double citizenship, i.e. the Kalydonians possessed, like the other Achaeans, both citizenship of their own city and citizenship of the federal state.  The existence of forms of federal organization along these lines can be seen in inscriptions from the late fifth century. A Som[ ] ophon Achaios Olenios shows up in the famous inscription from Sparta listing contributors and contributions to Sparta’s war fund (edited by W.T. Loomis with new fragments).  This man from Olenos, an Achaean city west of Patras, is indicated with a sequence of personal name, ethnic name, and city ethnic, as will become usual in later times. This suggests the existence of a double level of citizenship, tied to Olenos’ membership in the Achaean state.  Dates proposed for this inscription vary between the Peloponnesian and the Corinthian War. An Attic honorary decree from the year 399 BCE shows a similar situation: the honoree is a certain Aristeas, an Achaean from Aigion (ton Akhaion ton Aigia).  These documents should be compared to a recently published inscription from Gorgippia, a Milesian colony on the northern shore of the Black Sea. It is a grave inscription dated between 490 and 480 BCE and commemorating one Philoxenos, son of Kelon, who came “from Helike of the Peloponnese” (Pelaponnaso ex Helikes). The inscription does not yet refer to Helike as Achaean; rather, in order to specify the location of the distant city of the deceased, it mentions its location in the Peloponnese. 
- While sources that concentrate on Panhellenic or Peloponnesian developments, as already pointed out, show the Achaeans as rather inactive and neutral, they did engage in noteworthy political activities in a specific area: the coastal region of the Gulf of Corinth facing Achaean territory. Expanding their range of action across the gulf, the Achaeans were also crossing their ethnic borders in the strict sense of the word. In the Homeric Catalogue of Ships the cities of Pleuron and Kalydon were still Aetolian,  but during the archaic and classical ages they had drifted apart from Aetolia and in the fifth century according to Thucydides they were located in a region called “Aeolis.”  With this extremely ambivalent designation, the inhabitants of the coastal region between Oiniadai and Kalydon were possibly trying to relocate themselves on the map of Greek ethnic identities in a way that facilitated cooperation between their region and (for instance) Achaeans, Boeotians, and Corinthians, and at the same time separated them decidedly from Aetolia in the strict sense. The integration of Kalydon in the Achaean koinon, which cannot be precisely dated, is not to be explained only as a consequence of some specific political situation, but rather as the result of close economic and cultural relations, which grew over a long time. The contacts seem to have been especially close between the coastal areas around Kalydon and Patrai. This is shown by several indices: the place-name Olenos is found both in Achaea and on the Aetolian coast facing Achaea;  according to Thucydides, the people of Zakynthos, at the entrance of the Gulf of Corinth, were descended from the “Achaeans of the Peloponnese”— whoever exactly these Achaeans should be understood to be;  and when Achaeans participated in Pericles’ expedition against Oiniadai in the mid-fifth century, this probably happened against the background of the preexisting political project aiming to take control of the Aetolian-Acarnanian coast and create there a sphere of influence.  If the Athenians had successfully established a lasting foothold in Oiniadai, they would probably have left the city to the Achaeans, by the same token as they gave nearby Naupaktos to the Messenians. In any case, during the fourth century Pleuron, Kalydon, and for a while also the Western Locrian city of Naupaktos and possibly other places on the Aetolian and Locrian coast such as for instance Phana, belonged to the Achaeans.