The history of the island is lost in the paths of time. Particularly, Kimolos has been known since antiquity mainly because of the famous chalk that was mined here and then distributed throughout the ancient world. The chalk of the island was in such great demand that Kimolos minted its own coins. In addition, the excavations carried out on the island brought to light a number of findings from the geometric, archaic, Greco-Roman era as well as from the first Christian years. According to these findings, in the area of ​​the strait that connected the island of Agios Andreas with the mainland, there was an ancient city. The same city was inhabited until the first Christian times and then sank in the sea by a strong earthquake. Indeed, at the bottom of the strait one can see when the sea is calm, the ruins of this lost state. It should be also noted that remains of the geometric and archaic era were also found in Polykastro, and that Kimolos was a tax subject to the Athenians.