From the Archaic times on, it seems that rivalry arose between Helike and its neighbor city of Aigion over the seat of the Achaean koinon focusing around the function of the two major sanctuaries located in this region: the sanctuary of Helikonios Poseidon situated in Helike’s territory and of Zeus Homagyrios/Homarios lying in the bordering zone between Helike and Aigion toward the Selinous river, the natural geographical boundary between the two cities. The panhellenic Ionian sanctuary of Helikonios Poseidon located in Helike, the capital city of ancient Achaea on the southwestern shore of the Gulf of Corinth, became the political and religious seat of the area since its foundation in the Mycenaean period and kept this position for many centuries.