Since the early Bronze Ages, the area around the river Neretva was inhabited by the Illyrian tribe Daorsi. The Daorsi had their centre in a fortified town near the village Ošanići near Stolac, today an archaeological site known as Daorson.

Greek mythology tells us that Illyrius, the progenitor of the Illyrians, was the son of the goddess Harmonia and the Phoenician Cadmus. Following the orders of his father, the Phoenician king Agenor, Cadmus went on a pursuit of his sister Europa, who was abducted by Zeus. Cadmus did not dare to return home without completing his task, so that after numerous wanderings with his crew, he settled down in Boeotia in Greece, where he founded the city of Thebes. He married Harmonia, the daughter of Ares and Aphrodite, and following a prophecy he went among the Illyrian Enchelei to become their king. The people Cadmus governed were named after his son Illyrius. In old age, Illyrius’s parents Harmonia and Cadmus turned into snakes and continued their eternal lives in this shape.

Following his birth, Illyrius was enveloped by a snake that transmitted his magical powers to him. Philological research has shown that the great mythical snake of the Indo-European Hittites carried a name of the same root. Her name was Illuyanka, and she had a very significant role in the Illyrian religion, so that the name of the Illyrians can be linked to this animal.