 The authors reported that evidence for the production of such complex bronzes disappears at the end of the 5th millennium coinciding with the "collapse of large cultural complexes in north-eastern Bulgaria and Thrace in the late fifth millennium BC".Tin bronzes using cassiterite tin would be reintroduced to the area again some 1500 years later.The Aegean Bronze Age begins around 3200 BC
when civilizations first established a far-ranging trade network.