The Dacians are first mentioned in the writings of the Ancient Greeks. Herodotus described them as “the noblest as well as the most just of all the Thracian tribes”, and Thucydides noted they were armed as mounted archers.
In 82 BC, Burebista ruled over the Geto-Dacians, reorganising the army and attempting to raise the moral standard of the people by persuading them to cut their vines and give up drinking wine. During his reign, the Dacian Kingdom expanded to its maximum extent, conquering the Bastarnae and Boii, and gaining authority over Greek towns on the Black Sea, Olbia and Apollonia. In 53 BC, Caesar stated that the Dacian territory was on the eastern border of the Hercynian Forest.
After Burebista’s death in 44 BC, Dacia plunged into internal strife, splitting into several rival states. Stability was restored when Duras and later Decebalus managed to reunite the kingdom. Strabo, writing around AD 20, noted that the Dacians inhabited both sides of the Tisza river. In AD 85, the Dacians attacked Moesia, resulting in the death of its governor, and initiating a series of conflicts with the Roman Empire. The Romans gained a strategic victory at Tapae in AD 88, but Domitian offered favourable terms to the Dacians, recognising Roman suzerainty.
However, Emperor Trajan restarted the conflicts in AD 101-102 and again in AD 105–106, ultimately leading to the annexation of most of Dacia and its reorganisation as the Roman province of Dacia Felix. Trajan’s conquests brought the Roman Empire to its greatest extent.
In AD 87, Roman troops under Cornelius Fuscus were defeated by the Dacians, and Cornelius Fuscus was killed by authority of their ruler, Decebalus. Following this victory, Decebalus took the name of Diurpaneus. In AD 101-102, the Romans besieged the Dacian capital, Sarmizegethusa, and occupied part of the country. In AD 105, with Roman troops pressing towards Sarmizegethusa, Decebalus sought terms, but ultimately committed suicide to avoid capture.
Following Decebalus’ death in AD 106, Dacia was annexed by the Roman Empire. The Romans abandoned Dacia in AD 271–275 during the reign of Emperor Aurelian, and the region was subsequently settled by various groups.
After the Roman withdrawal, the territory of Dacia was inhabited by groups including the Victohali, Taifals, and Thervingians. The Gepids used it as a base until it was destroyed by the Lombards in 566. The Avars dominated the region for 230 years, until their kingdom was destroyed by Charlemagne in 791. Slavic people also arrived in the region during this period.
The extent and location of Dacia varied throughout its history. Ptolemy’s Geographia, written a few decades after the Roman conquest, included the boundaries of Dacia, which scholars interpret as the region between the rivers Tisza, Danube, upper Dniester, and Siret.