The prehistory of Southeastern Europe, defined roughly as the territory of the wider Southeastern Europe (including the territories of the modern countries of Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Greece, Romania, Moldavia, Montenegro, Serbia, Slovenia, and European Turkey) covers the period from the Upper Paleolithic, beginning with the presence of Homo sapiens in the area some 44,000 years ago, until the appearance of the first written records in Classical Antiquity, in Greece as early as the 8th century BC.

After the period that followed the arrival of the Dorians, known as the Greek Dark Ages or the Geometric Period, the classical Greek culture developed in the southern Balkan peninsula, the Aegean islands and the western Asia Minor Greek colonies starting around the 9th or 8th century BC and peaking with the democracy that developed in 6th and 5th century BC Athens. Later, Hellenistic culture spread throughout the empire created by Alexander the Great in the 4th century BCE. The Greeks were the first to establish a system of trade routes in the Balkans, and in order to facilitate trade with the natives, between 700 BC and 300 BC they founded a number of colonies on the Black Sea (Pontus Euxinus) coast, Asia Minor, Dalmatia, Southern Italy (Magna Graecia) etc.

By the end of the 4th century BC Greek language and culture were dominant not only in the Balkans but also around the whole Eastern Mediterranean. In the late 6th century BC, the Persians invaded the Balkans, and then proceed to the fertile areas of Europe. Parts of the Balkans and more northern areas were ruled by the Achaemenid Persians for some time, including Thrace, Paeonia, Macedon, and most Black Sea coastal regions of Bulgaria, Romania, Ukraine, and Russia. The Thracian Odrysian empire - the Odrysian kingdom, was the most important Daco-Thracian state union, and probably was founded in the 470s BC, after the Persian defeat in Greece. Other tribal unions existed in Dacia at least as early as the beginning of the 2nd century BC under King Oroles. The Illyrian tribes were situated in the area corresponding to today's Adriatic coast.