I think it's sherpa. I couldn't find a mongolian link to gurkha (or whatever spelling) who came from the west? I did find a mongolian link to sherpa though, who came from the east:-
i'm going to put the cat among the pigeons! While checking out Nepal I discovered that some of the people living there are called tharus, therefore I put the answer down as tharia! My crosswords are already enveloped so I'm not changing now.