The Vinča culture which flourished in the 5th–4th millennia BC included over 18 sites in the Niš area. 31 sites in the Nišava basin are dated to the Eneolithic (3200–2000 BC). Several migrations from the Black Sea steppes into the Balkans change the ethnic picture; natives and immigrants mix and result in the formation of the first Indo-Europeans in the Balkans. The Bubanj–Hum culture is found in its early phase in Pomoravlje, but not in the Niš area, until bearers of Bubanj–Hum II connected to the late phase of the Baden culture arrive into the Nišava basin. The Niš area was inhabited by the Triballi, a tribe described as a specific people by ancient writers. Their ethnic affiliation is unknown, as linguistical research is inconclusive, while it is known that their territory was recognized in antiquity as Thracian, their relation to Thracians were older and stronger than that to Illyrians, and that they through history mixed with both Thracian and Illyrian elements. Scarce archaeological finds and onomastics indicate the presence of Thracian, Illyrian, Celtic and Dacian populations members in the Niš area in antiquity. The Triballi inhabited the Great Morava valley in the 5th century BC. In 279 BC, during the Gallic invasion of the Balkans, the Scordisci tribe defeated the Triballi and settled their lands. At the time of the conquest of the Balkans by Rome in 168-75 BC, the Niš area was used as a base for operations. Naissus was first mentioned in Roman documents near the beginning of the 2nd century CE, and was considered a place worthy of note in the "Geography" of Ptolemy of Alexandria. In the early Roman period, Naissos (as Naissus) was viewed of as Dardanian territory, while onomastics show that the population was predominantly Thracian. The Romans occupied the town in the period of the "Dardanian War" (75-73 BC), and set up a legionary camp. The city (called "refugia" and "vici" in pre-Roman relation), because of its strategic position (Thracians were based to the south) developed as an important garrison and market town of the province of Moesia Superior. The Romans built the "Via Militaris" in the early 1st century AD, with Naissus being one of the key towns.