Syrmia is a region of the southern Pannonian Plain, which lies between the Danube and Sava rivers. It is divided between Serbia and Croatia. Most of the region is flat, with the exception of the low Fruška gora mountain stretching along the Danube in its northern part.

Pannonia was a province of the Roman Empire bounded on the north and east by the Danube, coterminous westward with Noricum and upper Italy, and southward with Dalmatia and upper Moesia. Pannonia was located in the territory that is now western Hungary, western Slovakia, eastern Austria, northern Croatia, north-western Serbia, northern Slovenia, and northern Bosnia and Herzegovina.