I am looking for the title of a 1970's (maybe) movie....?

This was a movie whose plot went something along the lines of an expedition financed by a woman whose husband had gone missing on a previous expedition...eventually husband is found in an alternate type of universe ..there are tribes of humans..the husband has become a type of leader of one tribe...a "great teacher" he is called. Wish I could give some more info....sorry the whole thing is a little foggy...if anyone could help it would be much appreciated!!! Thank you!!!