Corinthians realized that Isthmus was, not only a defense line, but also important for the navigation and specifically that its small width could make it easier to the ships to pass from the Corinthian to Saronic Gulf and vice versa. This would ease the communication between West and East and avoid the dangerous and distant trip around Peloponnese.
Around 9th century, they started building a way across Isthmus from the today’s region of Posidonia and ended up to Sxinouda (today known as Kalamaki). The way was not straight in order to avoid the uphill and downhill, so it won’t be too exhausting for those who carried the ships. The way was named Diolkos and it was the first international track-based mode.
Diolkos operated for 1600 years, until 1154, according to the map of the arab geographer Al – Idrisi.