Original sentence: It is one of the oldest mountain ranges of the Alps, and it was one of the last ones to be opened to public tourism towards the end of the 20th century.It is relatively unspoiled.Its geographical extension is the basin of river Guil, a tributary of the Durance
Edited sentence: Because of this, it was able to protect itself from massive tourism that has destroyed so many other beautiful areas of the world.It is one of the oldest mountain ranges of the Alps, because it was one of the last ones to be opened to public tourism towards the end of the 20th century.Its geographical extension is the basin of river Guil, an affluent of river Durance