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."