Hercynian Forest  The Hercynian Forest was an ancient and dense forest that stretched eastward from the Rhine River across southern Germany and formed the northern boundary of that part of Europe known to writers of antiquity. The ancient sources are equivocal about how far east it extended. All agree that the Black Forest, which extended east from the Rhine valley, formed the western side of the Hercynian. Across the Rhine to the west extended the "Silva Carbonaria" and the forest of the Ardennes. All these old-growth forests of antiquity represented the original post-glacial temperate broadleaf forest ecosystem of Europe. Relict tracts of this once-continuous forest exist with many local names: the Black Forest, the Ardennes, the Bavarian Forest, the Vosges, the Eifel, the Jura Mountains, the Swabian Jura, the Franconian Jura, the Polish Jura, the Palatinate Forest, the Teutoburg Forest, the Argonne Forest the Odenwald, the Spessart, the Rhön, the Thuringian Forest, the Harz, the Rauhe Alb, the Steigerwald, the Fichtelgebirge, the Erzgebirge, the Riesengebirge, the Bohemian Forest, and the forested Carpathians. The Mittelgebirge seem to correspond more or less to a stretch of the Hercynian mountains. Many present-day smaller forests were also included like the Bienwald and the Haguenau Forest. The Hercynian Forest probably extended to the Białowieża Forest. "Hercynian" has a Proto-Celtic derivation, from "ɸerkuniā", later "erkunia". Julius Pokorny lists Hercynian as being derived from *' "oak" (compare "quercus"). He further identifies the name as Celtic. Proto-Celtic regularly loses initial ' preceding a vowel, hence "Hercynia " (the "H-" being prothetic in Latin, the Latin "y" signifying a borrowing from Greek). The corresponding Germanic forms have an "f-" by Grimm's Law: Old English "firgen" = "mountains", Gothic "faírguni" = "mountain range". The assimilated ' would be regular in Italo-Celtic, and Pokorny associates the Celtiberian ethnonym "Querquerni", found in Hispania in Galicia.