From the newly conquered land, Trajan organized the Roman province of Dacia, whose capital, Ulpia Trajana, stood on the site of Sarmizegetusa. Many Getae resisted Roman authority and some fled northward, away from the centers of Roman rule. Trajan countered local insurrection and foreign threat by stationing twÍÍÍÍo legions and a number of auxiliary troops in Dacia and by colonizing the province with legionnaires, peasants, merchants, artisans, and officials from lands as far off as Gaul, Spain, and Syria. Agriculture and commerce flourished, and the Romans built cities, fortresses, and roads that stretched eastward into Scythia.

In the next 200 years, a Dacian ethnic group arose as Roman colonists commingled with the Getae and the coastal Greeks. Literacy spread, and Getae who enlisted in the Roman army learned Latin. Gradually a Vulgar Latin tongue superseded the Thracian language in commerce and administration and became the foundation of modern Romanian. A religious fusion also occurred. Even before the Roman invasion, some Getae worshiped Mithras, the ancient Persian god of light popular in the Roman legions. As Roman colonization progressed, worshipers faithful to Jupiter, Diana, Venus, and other gods and goddesses of the Roman pantheon multiplied. The Dacians, however, retained the Getian custom of cremation, though now, amid the ashes they sometimes left a coin for Charon, the mythological ferryman of the dead.

Data as of July 1989