The Didiron mountain range was a mountain range on Vissia that ran through the upper plains of the Great Continent. The range was located on a central plateau, with flora and fauna varying greatly on either side of the plateau.
In his time aboard the Enterprise, in 2153, the Cogenitor Charles learned about the range by reading about it. Charles Tucker III said that to read about something, like this geological landmark, was one thing, but to experience it was something more. (ENT: "Cogenitor")