The Ardennes, also known as the Ardennes Forest or Forest of Ardennes, is a region of extensive forests, rough terrain, rolling hills and ridges. Geologically, the range is a western extension of the Eifel, and both were raised during the Givetian age of the Devonian, as were several other named ranges of the same greater range.
The Ardennes proper is primarily in Belgium and Luxembourg, but stretches well into Germany and France and geologically into the Eifel; most of it is in southeastern Wallonia, the southern and more rural part of the Belgium. The eastern part of the Ardennes forms the northernmost third of the Grand Duchy of Luxembourg, also called "Oesling". On the southeast the Eifel region continues into the German state of the Rhineland-Palatinate.
The trees and rivers of the Ardennes provided the charcoal industry assets that enabled the great industrial period of Wallonia in the 18th and 19th centuries, when it was arguably the second great industrial region of the world. The greater region maintained an industrial eminence into the 20th century, after coal replaced charcoal in metallurgy.