Inhabited by the ancient Dacians, today's territory of Romania was conquered by the Roman Empire in 106, when Trajan's army defeated the army of Dacia's ruler Decebalus. The Roman administration withdrew two centuries later, under the pressure of the Goths and Carpi.
Two theories account for the origin of the Romanian people. One, known as the Daco-Roman continuity theory, posits that they are descendants of Romans and Romanized indigenous peoples living in the Roman Province of Dacia, while the other posits that the Romanians are descendants of Romans and Romanized indigenous populations of the former Roman provinces of Illyria, Moesia, Thrace, and Macedon, and the ancestors of Romanians later migrated from these Roman provinces south of the Danube into the area which they inhabit today.
According to the first theory, the Romanians are descended from indigenous populations that inhabited what is now Romania and its immediate environs: Dacians and Roman legionnaires and colonists. In the course of the two wars with the Roman legions, between AD 101–102 and AD 105–106 respectively, the emperor Trajan succeeded in defeating the Dacians and the greatest part of Dacia became a Roman province. The colonization with Roman or Romanized elements, the use of the Latin language and the assimilation of Roman civilization as well as the intense development of urban centers led to the Romanization of part of the autochthonous population in Dacia. This process was probably concluded by the 10th century when the assimilation of the Slavs by the Daco-Romanians was completed.
According to the south-of-the-Danube origin theory, the Romanians' ancestors, a combination of Romans and Romanized peoples of Illyria, Moesia and Thrace, moved northward across the Danube river into modern-day Romania. Small population groups speaki