Roman Umbria is a modern name for one of the 11 administrative regions into which the emperor
Augustus divided
Italy. The main source for the regions is the
Historia Naturalis of
Pliny the Elder, who informs his readers he is basing the geography of Italy on the
discriptio Italiae, "division of Italy," made by Augustus. The
Sexta Regio ("6th Region") is called
Umbria complexa agrumque Gallicam citra Ariminium, "
Umbria including the Gallic country this side of
Rimini."