Burebista (Ancient Greek,"Βοιρεβίστας") is widely considered to be the greatest king of Dacia. He ruled between 82 BC and 44 BC. He unified the Thracian population from Hercynia (today's Moravia) in the west, to the Bug River in the east, and from the northern Carpathians to Dionysopolis. His capital was called Argedava (or Sargedava) and was located near Costeşti in the Orăştie hills of southwestern Romania.

The spiritual center of the kingdom was called Kogaion (or Kagaion, the holy mountain) by the ancient geographer Strabo. It is believed to have been located somewhere in the Bucegi mountains. According to the historian Jordanes (in his work Getica), the greatest priest and adviser of Burebista was Dicineus (Deceneus), who held "almost royal powers" and taught the Dacians the belagines laws, ethics and sciences, including physics and astronomy.

Between 60 and 40 BCE it was fought the so called Daco-Celtic war, which saw the dacians attacking the celtic Scordisci, Boii and Taurisci confederations. Burebista defeated the once powerful Boian confederacy, and its Taurisci allies, destroying also the Oppidum of Bratislava, their capital.

Burebista sided with the inhabitants of the Greek cities on the Western coast of the Black Sea from Apollonia to the Danube Delta (South of the Danube) when they were occupied by Varro Lucullus, the proconsul of the province of Macedonia during the second Mithridatic War (74 BC–72 BC). The Dacians defeated the Roman army of Gaius Antonius Hybrida near Histria. As a result of this battle, the Greek cities of Tomis, Callatis, Dionysopolis and Apollonia agreed to become part of Burebista's kingdom.

Burebista continued his incursion in the region, conquering the Celtic Aliobrix (Cartal, southern Bessarabia, now part of Ukraine), Tyras and Odessos and destroying Olvia.

In 48 BC, Burebista sided with Pompey during his struggle against Julius Caesar in the Roman civil war. After Caesar emerged as victor, he planned on sending legions to punish Burebista, but he was assassinated in the Senate before he could do so, on March 15 44 BC. Burebista died the same year, but whether he was assassinated in a court plot or his death had natural causes is a matter that remains uncertain.