The Dacians were first mentioned in Ancient Greek writings by Herodotus and Thucydides. Some historians believe they were Indo-Iranian nomads who formed the Geto-Dacian people.
The Dacian kingdom existed from 82 BC to AD 106, reaching its peak under King Burebista. After two wars with Emperor Trajan, the population was dispersed and the capital, Sarmizegetusa Regia, was destroyed. The Romans rebuilt it to serve as the capital of the Roman province of Dacia.
It is possible that a group of "Free Dacians" remained outside the Roman Empire in modern-day Northern Romania until the start of the Migration Period. The extent and location of Dacia varied in its three distinct historical periods.