Dacians came into conflict with the
Romans who, during the same period, were attempting to extend their
control over the Balkan region and to push the northern border of their
empire up to the natural barrier formed by the Danube River. In a
series of campaigns between A.D. 101 and 106, the Roman emperor Trajan
succeeded in conquering the areas known as Banat, Oltenia, and Walachia
and in finally reducing the Dacian stronghold in Transylvania. After
consolidating and unifying his control over the people, Trajan fortified
the area, stationed Roman legions in garrisons at strategic points, and
organized the region to serve as a province of the Roman Empire.

As a border province, Dacia developed rapidly and became one of the most
prosperous in the empire. Colonists were brought in from other parts of
the empire, cities were built, agriculture and mineral resources were
developed, and profitable commercial relations were established with
other regions under Roman control. The province proved vulnerable to
periodic barbarian incursions, however, and toward the end of the third
century the Roman emperor Aurelian was forced to abandon Dacia and
withdraw the Roman troops to defend similarly threatened areas farther
to the south.

Aside from the romanization of the native population, little evidence of
the occupation survived the Roman evacuation of Dacia. Among the traces
of the Roman presence remaining were the vestiges of Christianity
introduced in the second century and the legacy of the name of the
future state of Romania as well as the Latin basis for its language.

Lacking natural geographical barriers to invasion from the east and
south, the greater part of the Dacian territory was overrun by
successive waves of barbarian invaders for ten centuries after the
withdrawal of the Romans. Little is known of the fate of the Daco-Roman
population during this long, turbulent period until new settlements
inhabited by a Latin-speaking people known as Vlachs emerged on the
Romanian plains in the eleventh century. Although historic records are
lacking, these Vlachs were believed to be descendants of the earlier
Daco-Roman colonists, many of whom either sought refuge in the
Carpathian Mountains of Transylvania or migrated south of the Danube
River to escape the invaders. Having survived, they returned to
reestablish themselves in their historic homeland.

The succession of barbaric invasions exploited and devastated the
country.