Mythology says that the name of the island was given by its first settler, Kimolos.
Little is known about the history of the island. In the Middle Ages, it was perhaps called Echinoussa, the island of the Echidnas
. Throughout its history, it was connected to Milos, whose fortunes it followed. In the Middle Ages it was occupied by the Venetians and was called Arzantiera.
The island was also known for its trade in chalk, a type of primary rock used in porcelain and which gave its name to the white rock, the chalk known from blackboards.
The ancient city, before it sank, was located in the west of the island in the current location of "Hellenic". What remains of the city is located on the islet of Agios Andreas, opposite Hellini, where ruins of the houses and tombs of the ancient city were found at the bottom of the area.
According to the archaeological finds, Kimolos has been continuously inhabited, at least since the late Neolithic era. The rich Greek imagination wanted to owe its name to its first settler, Kimolos, husband of the daughter of Taurus, Sidis.
She was given the epithets Echinoussa (island of the Urchins) and Echidnussa (island of Echidnon). The sunken state and necropolis in the Hellenic region have yielded Mycenaean, Geometric, Archaic and Classical finds. This city seems to have been inhabited by the Kimoli at least until the early Christian years. In the 5th century BC it belonged to the Athenian alliance and its government was organized according to the standards of the Athenian democracy. There was a parliament and a Municipality and the power was exercised by three lords and three treasurers. The patron goddess was Athena, while Artemis, Hermes and Poseidon were still worshipped.
In the 3rd century B.C., Kimolos issued its own coins, a possibility given to it by the large exports of the "Chalkland" and its excellent figs. The dispute between the Kimoli and Milos over the ownership of Polyaigo and the nearby islets began in 416 BC and ended shortly after 338 BC with the decision of the court of the Argives and with the victory of the Kimolos who still retain the right to this day this.
The little information that exists about the Roman and Byzantine eras mainly concerns the "chalk land" trade. At the top of Paliokastro hill there are ruins of a castle and tower of unspecified age. It passed from the Byzantines to the Franks in 1207 when Markos Sanoudos conquered it. Franks, Venetians, pirates of all nationalities and Turks became the cause of the serious reduction of the population and the economic withering of the island. The danger that all the previous ones represented for the locals left a visible trace today: the Medieval Castle which was the only settlement on the island. During the first Russo-Turkish war, Orloff drew up detailed maps of the island, either in search of the legendary silver mines or, according to others, because of the island's strategic location.

Source: Municipality of Kimolos
http://www.kimolos.gr/