According to an ancient tradition, the Carians, who were later expelled by the Minoans, were the first residents of Thera. Herodotus claims that the Phoenicians were the ancient residents of Thera. They were left there by Cadmus on his journey to find Europa. One of his relatives, Memvliarus, stayed along with them on the island and he is considered the first settler of Anafi. Thera remained under their control for eight generations until the arrival of Theras from Sparta, who was the son of Autesion and a descendant of Cadmus. He came to the island along with other Laconians and Minyans and named it after himself. According to Pliny, Thera was called Kalliste when it first emerged from the sea.
Archaeological data indicate that before the volcano eruption in the middle of the 2nd millennium BC, the island of Thera was round and Therasia and the rest of the smaller islets were a part of it. The settlement in Akrotiri, in the north of the island, dates back to the Late Neolithic and the Early Bronze period (4th – 3rd millennium BC). It was there that one of the most important prehistoric settlements of the Aegean bloomed during the Middle Cycladic period (first half of the 2nd millennium BC). By the 18th century BC, a town had developed. However, it was destroyed by a major earthquake in the early 17th century BC. The town was rebuilt and extended over a large area. It had an elaborate canalization and carefully designed multi-storey buildings with wonderful murals, furniture and utensils that indicate the level of cultural development and prosperity of the town. The numerous excavation findings highlight the cosmopolitan nature of Akrotiri’s port that had a developed network of trade relations with Minoan Crete, mainland Greece, the Dodecanese, Cyprus, Syria and Egypt.
The town reached its peak during the Late Cycladic period. However, according to various scientific data, it was buried under thick layers of ash around 1630 BC after the major volcano eruption. The residents left the island in time taking along with them whatever valuables they could carry.
Findings in Monolithos indicate that new settlers came to the island during the Mycenaean period (14th – 12th century BC).