Dacia was an area in ancient central Europe, bounded by the Carpathian Mountains, largely covering Transylvania in modern Romania. The Dacians were of Thracian stock, related to the Getae. They traded with the Greeks, adopting their coins, and were culturally influenced by the Scythians and Celtic invaders. King Burebista unified and expanded Dacia in 60/50 BC, creating a regional power. However, the kingdom broke up after his assassination. The Romans gradually pushed the Dacians back from the Danube. The emperor Trajan eventually subdued the region, turning it into a Roman province for over a century and a half.