"The provinces of the Danube soon acquired the general
appellation of Illyricum, or the Illyrian frontier, and were
esteemed the most warlike of the empire; but they deserve to
be more particularly considered under the names of Rhætia,
Noricum, Pannonia, Dalmatia, Dacia, Mœsia, Thrace, Macedonia,
and Greece. … Dalmatia, to which the name of Illyricum more
properly belonged, was a long but narrow tract, between the
Save and the Adriatic. … The inland parts have assumed the
Sclavonian names of Croatia and Bosnia."
_E. Gibbon,
Decline and Fall of the Roman Empire,
chapter 1._
See, also, ROME: A. D. 394-305.