It was when the Greeks settled on the Western shore of the Black Sea (Pontus Euxinus), where they set up the colonies of Tomis, Histria, Callatis, Olbia and Appolonia, that the local Thracians came into contact with the Greek world. The Greek historian Herodotus was the first to mention the population North of the Danube as Getae (Getians).In the 6th century B.C., there are records of the Geto-Dacians, an ethno-historical entity branched out from the great Thracian trunk. The first archaeological findings relate to the Basarabi culture in Dobrudja materialized in an exquisite kind of pottery. The Geto-Dacians inhabited the vast area that stretched between the Northern Carpathian chain and the Balkan mountains.Geto-Dacian society flourished under king Burebista (ca 82-44 B.C.), a contemporary and opponent of Caesar, and a friend of Pompey. Around the year 70 B.C., external conditions being propitious and Burebista's political and military actions successful, the Geto-Dacian people had a unique and firm rule, and a strong organization.Burebista's country, rooted in the former social and political tradition, was strengthened by the king's conquest of Greek cities, like Tomis, Histria and Callatis on the Black Sea shore, and by eliminating the threat of Celtic invasion. In this way, Burebista came to rule over the whole Thracian-Geto-Dacian world, from the Haemus Mountains (the Balkans) to the Wooded Carpathians, from Tyras (the Dnestr) to the Tisza.Controlling both sides of the Danube, Burebista was "the first and the greatest of the Thracian kings", as he is referred to in writing by Acornion of Dyonisopolis. The unifying centre of the Geto-Dacian state lay in the Orastie mountain zone (Sureanu) - a natural Transylvanian stronghold; there, Burebista developed a whole system of fortifications, which was to be continued by his followers Dicomes, Scoryllo, Cotiso.His successful unifying endeavour, which led to the unity of the Geto-Dacian people, language and civilisation, made the king feel stronger, a fact which led him into believing that he was capable of measuring his military strength with that of the Romans. He was supported by the great priest Daecaeneus. Intent upon taking advantage of the civil war between Caesar and Pompey, he lent his support to the latter. Unfortunately, Caesar, emerging victorious, planned to take revenge on the Dacians in war. But his murder in the year 44 B.C. delayed an armed confrontation by some one hundred and twenty years. Shortly after Caesar's death, Burebista himself was overthrown by a plot of the aristocracy discontented with the king's absolute power. After his fall, the state weakened and lost part of its territory.The Geto-Dacians were to witness a new period of cultural and political prosperity when Decebal (A.D. 87-106) acceded to the throne. Geto-Dacian civilisation was by then at its climax. In the 1st century B.C., as the Roman Empire was expanding, the Danube became the border between the Roman Empire and the Geto-Dacians. Dobrudja was already under Roman rule beginning with the reign of Augustus.Eventually, the Romans did declare war on the Dacians, after a first confrontation (A.D. 87-89), and they waged two bloody wars (A.D. 101-102 and 105-106). The Geto-Dacians were defeated, the Empire led by Trajan extended its bounds over the Danube and turned part of Dacia into a Roman imperial province. Two monuments commemorate the events: one is Trajan's Column, in Rome, the work of Apollodorus of Damascus (A.D. 113), and the other is Trophaeum Traiani, at Adamclisi (A.D. 109).