When I was a kid, probably around 1980 or so, I watched a western movie I never forgot, but I never saw it again, nor ever knew what the title was.
It was a western and somehow evolved around a white woman, who was found among a group of dead cowboys (or something like that). She reminded me a bit of Maryam d’Abo

http://www.imdb.com/name/nm0001881/?ref_=tt_cl_t2

But this is so long ago, I could be wrong. But she was wite and had long hair, blond/brownish (not black hair at least). Another group of travelling cowboys came and picked her up. Then strange things started to happen – they died one by one too. In the end it turned out it was the woman who was the killer. She was a sort of legend come true that the cowboys had talked about in the movie – she used knives, and often a bow and arrow, assisted (in the ending scene) by an eagle who gave the bow to her. The scene ended by showing another group of cowboys coming in the distance, suggesting the whole thing would happen again.
I hope I am lucky that this rings a bell for someone?
Regards
Martijn