Possibly derived to some extent from Ortelius' own two sheet map of the Roman Empire, which appeared in 1571. Further, this map is based on classical sources, such as Salustius, Plinius, Herodotus, Strabo and Dionysius.
This map belongs to a series of historical maps known as the Parergon Theatri which appeared from 1579 onwards, sometimes as a separate publication and sometimes incorporated in the Theatrum.