Etmology
Doon or Dun (Hindi: दून) is a local word for valley, particularly an open valley in the Sivaliks or between the Sivaliks and higher Himalayan foothills. Other valleys in this region have names like Patli Dun, Kothri Dun, Pinjore Dun in Himachal Pradesh.
Read more about this topic: Doon Valley