The Quest for Fire (La Guerre du feu). The other quintessential 80s caveman movie, with Ron Perlman, Rae Dawn Chong and Everett McGill. I recall it being quite a big deal when I was about seven, but never actually watched it until yesterday.
A tribe of neanderthals (or heidelbergensis, depending on who's analysing the movie) keep a single flame burning in their home cave which they obtained from some natural source, and use it to light all their fires (since they don't know how to produce it themselves). After they get raided by their more apelike neighbours and lose the flame, three of them set out to find another source, eventually picking up a Cro-magnon/homo sapien girl after inadvertently rescuing her from cannibals, and getting into all sorts of shenanigans with her tribe.
Made to be a sort-of-accurate portrayal of paleolithic life (as best they understood it in 1981) it's a surprisingly engrossing film, considering the whole thing is delivered in stone age grunt-and-point vernacular and the plot basically boils down to "Fire gone, go find more, who that girl, watch out for mammoth."