The first people to leave lasting traces and cultural heritage throughout the Balkan region were the Thracians. Their origin remains obscure. It is generally proposed that a proto-Thracian people developed from a mixture of indigenous peoples and Indo-Europeans from the time of Proto-Indo-European expansion in the Early Bronze Age when the latter, around 1500 BCE, conquered the indigenous peoples. Thracian craftsmen inherited the skills of the indigenous civilisations before them, especially in gold working.^[9]

The Thracians were generally disorganized, but had an advanced culture despite the lack of their own proper script, and gathered powerful military forces when their divided tribes formed unions under the pressure of external threats. They never achieved any form of unity beyond short, dynastic rules at the height of the Greek classical period. Similar to the Gauls and other Celtic tribes, most Thracians are thought to have lived simply in small fortified villages, usually on hilltops. Although the concept of an urban center was not developed until the Roman period, various larger fortifications which also served as regional market centers were numerous. Yet, in general, despite Greek colonization in such areas as Byzantium, Apollonia and other cities, the Thracians avoided urban life.