The Romans commenced their military raids in the Carpathian Basin in 156 BCE when they attacked the Scordisci living in the Transdanubian region. In 119 BCE, they marched against Siscia (today Sisak in Croatia) and strengthened their rule over the future Illyricum province south of the Carpathian Basin. In 88 BCE, the Romans defeated the Scordisci whose rule was driven back to the eastern parts of Syrmia, while the Pannonians moved to the northern parts of Transdanubia.^[1] The period between 15 BCE and 9 CE was characterized by the continuous uprisings of the Pannonians against the emerging power of the Roman Empire.

The Roman Empire subdued the Pannonians, Dacians, Celts and other peoples in this territory. The territory west of the Danube was conquered by the Roman Empire between 35 and 9 BCE, and became a province of the Roman Empire under the name of Pannonia. The easternmost parts of present-day Hungary were later (106 CE) organized as the Roman province of Dacia (lasting until 271). The territory between the Danube and the Tisza was inhabited by the Sarmatian Iazyges between the 1st and 4th centuries CE, or even earlier (earliest remains have been dated to 80 BCE). Roman Emperor Trajan officially allowed the Iazyges to settle there as confederates. The remaining territory was in Thracian (Dacian) hands. In addition, the Vandals settled on the upper Tisza in the 2nd half of the 2nd century CE.

The four centuries of Roman rule created an advanced and flourishing civilization. Many of the important cities of today's Hungary were founded during this period, such as Aquincum (Budapest), Sopianae (Pécs), Arrabona (Győr), Solva (Esztergom), Savaria (Szombathely) and Scarbantia (Sopron). Christianity spread in Pannonia in the 4th century, when it became the empire's official religion.