The relationship between the region which would become Illyricum and Rome, especially the legal position and status of the region in the later Roman Republic, is not entirely clear due to inadequate sources. It is often assumed by modern scholarship that Illyricum was either a province with ‘vague boundaries’, being outside a provincial zone as an independent protectorate, or administered from other provinces. Wilkes denied the existence of any meaningful regional policy in this period after the potentially dangerous Macedonian kingdom had been destroyed. Future Illyricum is represented as a strategic backwater where Romans fought only to train armies and provide triumphs for the imperatores, a place from which Romans were actually in retreat in the second and early first century BC. Most recently, in an extensive discussion of the sources, Šašel Kos summarised Roman Republican political conduct in the region until Octavian as an ad hoc reaction to the regional crisis. There was no meaningful, systematic conquest; the Romans were gradually establishing their direct and indirect control over parts of the region, as a consequence of their military interventions.

The trans-Adriatic conduct of Rome from the Illyrian wars to Caesar's pro-consulship recognised two different, but interrelated, zones in the eastern Adriatic. Thus, two contrasting Roman approaches to foreign affairs emerged: expansionism and hegemonism overlapped and complemented each other.