I don’t remember much from this movie, other than it’s in color and must have been made in the 80s. It’s a somesort of sci-fi where a group of explorers explore some deep caverns and find a hidden subterranean society of human-like people with white hair (probably descents of aliens) who weave their hair to make clothes and rope. At the end of the movie, the explorers unwillingly trigger a cave-in and the human-like people are trapped / destroyed by the collapse.

Good luck !