By the time of the Peloponnesian War, Achaia's main cities were Patrai, Pellene, and Dyme. As the so-called 'Shipyard of Greece', Achaia was central in the conflict between Athens' Delian League and Sparta's Peloponnesian League. Given this, it drew the attention of the Cult of Kosmos, especially of The Silver Vein. Among them, Machaon made the military shipyard of Patrai his home, providing ships to whoever wished for them, as well as the Sage of the branch, Polemon the Wise, dwelt within the Teichos of Herakles in the mountains of Achaia, controlling the flow and ebb of the war as he willed.
In the 420s, Achaia was targeted by the Persian Order of the Ancients, specifically the Order of the Storm and the Magi of the branch, the Tempest. Coincidentally, also Darius and his son Natakas were in the region at the same time. The Spartan misthios Kassandra was asked by the latter two to help them deal with the former, and help the local refugees flee.
The region's economy was primarily concerned with ships and shipmaking, its inhabitants known to be skilled shipwrights and, as such, each city contributed to the region's naval construction in their own way. As a result, Achaia was essentially the shipyard of Greece, and its thriving economy ensured that it had a medium-sized population relative to the rest of Greece in the 5th century BCE. While it harbored abundant raw materials for ship building, vast tracts of land were deforested for this industry.
Achaia was made up of six regions:
- Erymanthos Peaks
- Istion Valley
- Kyllene Foothills
- Poseidon's Wrath
- Mount Panachaikos
- Scavenger's Coast
Behind the scenes
The emblem of Achaia in Assassin's Creed: Odyssey features a stylized trireme in gold on a red base, the former referencing Achaia's main export and the latter possibly referencing miltos, the red dye used to paint the ships and protect them from the elements. This also underlines the epithet of the region, "Shipyard of Greece."