Beak-spouted jug decorated with intersecting grooves, from the prehistoric settlement at Thermi. Bronze Age, Thermi I. Our knowledge of the Bronze Age on Lesbos is mainly based on the site of Thermi, which is the only prehistoric site of the island to have been systematically excavated. In the course of the Early Bronze Age (3000-2000 B.C.) the settlement passed through five successive stages, each of which constitutes a developmental phase and separate city, which belongs to the cultural sphere of the so-called Trojan civilization.