Excavations in Sifnos have revealed many ancient towns and fortifications. Historians believe that the first inhabitants of Sifnos island were the Pelasgus, followed by other tribes like the Phoenicians and Cares. The Minoan civilization of Sifnos Greece was destroyed after the Thera eruption in around 1,500 BC and then the Mycenaeans took over the island, as shown by the many Mycenaean findings that have been excavated on the island.
In the ancient times, Sifnos became prosperous by its gold and silver mines, which is why many Greek city-states occasionally tried to occupy the island. This prosperity is even shown by the Treasury of the Siphnians that the locals would keep in Ancient Delphi, a kind of storehouse for their valuable offerings to god Apollo. In the Medieval times, Sifnos island and the rest of the Cyclades were occupied by the Venetians, who established new towns, built watch towers and developed trade. This is when the village of Kastro (whose name means Castle) was established in Sifnos, with large economic and cultural development.
In the recent times, Sifnos island offered important help to the Greek Revolution of 1821 and became part of the first modern Greek State that was officially formed in 1829. Due to their rich tradition, the locals founded well-acknowledged schools that produced a new generation of Greek scholars, artists and politicians.