Always nice to see these daggers with iron mounts. In my minds eye these are definately Tibetan related. Keep in mind Tibet used to be a much lager country-
http://www.tibetmap.org/pw4br.html
In the maps you can see that Tibet was at one time larger than China, had part of Northern India, Bhutan and Nepal. Would imagine their area of influence would be approximately what the early border lines were.
Sometimes its difficult to say if something originated from one country because there can be such a blending of cultural influence. But until more is published on Bhutan, Nepal and Chinese arms and armor Tibet is my choice of labels for your dagger.
The clasp/attachment near the top of the hilt rings of Chinese or Mongolian design and taste.
rand