Historical sources confirm that the island of Kythnos was the oldest human settlement in the Cyclades. Important remains the settlement of Mesolithic (10,000 BC) found in the region because of Maroulas near LOTR, northeast of the island.
The archaeological findings in Slags dated 3000 years BC show that the island had exported metallurgical materials, especially iron, the other nearby islands. Later the island was inhabited by Kares, and then by Driopes and Ionians.
During the Roman period, the island is subject to constant raids by pirates caused a rapid decline in population.
In medieval times the island of Kythnos was under the sovereignty of the Franks and then the Venetians occupied for over 400 years and which gave the name of heat (for hot springs).
During the Ottoman period Kythnos seemed an island exerted on religious freedom, low population and constantly under pressure from the pirates.
The population was nearly decimated by the ongoing epidemics, particularly that of 1823.
Kythnos is one of the first islands to take sides against the Turks in the Greek struggle for independence and in accordance with the Greek kingdom was a place of exile for political prisoners.
In the nineteenth century as an island Kythnos was devoted to sheep farming and fisheries, rather isolated. Later, when discovered rich deposits of iron, the main economic livelihood, until World War II, represented by the mines. Forte was the migration of youth. The booming tourism brought the rest of the Cyclades barely touches the island of Kythnos because of difficulties in berthing of ships due to the deep waters of the bays.
Today the island is a Kythnos contemporary art in the use of alternative energy sources (solar and wind). Kythnos in 1983 was the seat of the first center for the production of wind power in Greece. Today offers the greatest power on the island. Moreover, many residents of the use of photovoltaic systems and solar panels.