The first Roman province, Sicily, was conquered after the First Punic War (241 BCE), and the Senate decided that it had to be ruled by a praetor. This meant that civil (not military) law was applied -at least under normal circumstances- and that the new territories were governed by magistrates who served a limited time. The Romans did never change these principles, even when the governors were no longer praetors.

It should be noted, however, that the Latin word provincia is in fact a military expression, indicating that a certain region was a general's responsibility. The first provinces were ill-defined, and it was only during the late republic that provinces started to have clearly defined borders.

When the emperor Augustus changed the empire into a monarchy, he was made governor of almost all provinces with legions, and used legati (representatives) to rule them. At the same time, the other provinces were governed by proconsuls, appointed by the Senate. So, there were two types of governors:

• Proconsuls. Usually, these men were former praetors. They governed the senatorial provinces and typically served twelve months. Only the rich provinces Asia and Africa were entitled to a proconsul who was an ex-consul.
• Legati Augusti pro praetore. These men served in the emperor's provinces with the armies (the imperial provinces). Usually, their term in office lasted thirty-six months, although the emperor Tiberius preferred longer terms.