 Julius Pokorny believed the name "Pannonia" is derived from Illyrian, from the Proto-Indo-European root "*pen-", "swamp, water, wet" (cf.English "fen", "marsh"; Hindi "pani", "water").Pliny the Elder, in "Natural History", places the eastern regions of the Hercynium jugum, the "Hercynian mountain chain", in Pannonia (present-day Hungary) and Dacia (present-day Romania).