The history of Halki is shadowed by the rest of the Dodecanese islands, especially Rhodes. Halki island has been inhabited since the prehistoric times and its name derives from the word "halki", which means purple. It is mentioned in the historical writings of Thucydides and Strabo. According to the Greek mythology, Titans were the first settlers followed by the Pelasgians who spent many years on this island leaving several constructions. Then there are traces of Caraes and Phoenicians.
In the ancient years, Halki appears as an ally of the Athenians which means that it was completely autonomous at that time. The centuries that follow, Halki shares the prime and decline of Rhodes. In the 7th century, it is conquered by the Arabs until 825. In 1204, the Venetians and Genovese arrive in Halki and restore the ancient acropolis, while building a fortress on top of Alimia islet.
During the 14th century, the Venetians give the island to the Assanti family from Ischia, who built a castle under the ruins of the ancient Acropolis. Among the several blazonries, the only one that survives is the one of the Great Master D Aubusson (1476-1530), who renovated the fortress after the catastrophic invasion from the Venetians. The entire population gathered at the castle in case of constant invasions.
In 1523, Halki is conquered by the Turks and in 1821 the island takes part in the Greek Revolution. Finally, in 1912, Halki and the rest of the Dodecanese islands are under the Italian rule. Together with Simi, Kalymnos, and Kastelorizo, they became important trading centers specializing in sponge fishing.