In the confused history of caveman movies, anachronism usually triumphs over fact. Most of the rather limited selection follow the Fred Flintstone theory of evolution, which suggests that, despite all the evidence and analysis, human beings shared their world with dinosaurs and other large, unfriendly beasts. That theory accounts for the two great classics of the genre - both, incidentally, a lot of fun - "One Million BC" (1940), which featured the muscular Victor Mature spearing a series of scary lizards, and "One Million Years BC" (1966), which established Raquel Welch, who looked terrific in a brief but well tailored outfit of animal skins.

The newest addition to the group, modestly entitled "10,000 BC," continues the grand tradition of wildly inaccurate portrayal of the behavior of primitive men and women in the millennia before history began. It includes the obligatory nonsense of extinct animals menacing some of the characters - gigantic ostriches in this case - but also shows some more or less plausible encounters of men and beasts, including a lot of footage of mammoths and a confrontation with a saber-tooth tiger, in a moment right out of folklore.

This illumination of the dawn of time also mixes a good deal of mystical mumbo jumbo with some creative interpretations of Stone Age cultures. The small tribe of humans who occupy the foreground of the action operate under the matriarchal guidance of a woman they call Old Mother, who prophesies (correctly) a highly unlikely attack by men on horseback. The invaders kill a number of people and abduct several of the tribe, including Evolet (Camilla Belle), beloved of the protagonist, D'Leh (Steven Strait), which sets the major plot in motion.

Most of the movie involves the efforts of D'Leh and some companions with equally improbable names to track the horsemen and rescue the captives. They set out across frigid, mountainous landscapes, then progress through jungles and deserts, either covering an enormous expanse of territory or experiencing a speeded-up version of the climate change of the Mesolithic era. In the journey they also join up with an African tribe, themselves victimized by the same attackers, whose chief conveniently knows the hunters' language; because he has saved a saber-tooth tiger from death, the animal spares D'Leh, which convinces the Africans that he should command the expedition against the horsemen.

Several other African tribes, spoiling for vengeance against their enemies, gladly join the growing army and make their way to a strange city where still another ethnic group, who look like some combination of Tibetans and Egyptians, governs with cruel force. There an immense body of slaves and a herd of domesticated mammoths - the picture departs still more drastically from reality - construct a huge pyramid in honor of some hideously withered elderly personage known as Almighty. The pyramid itself resembles both South American and Egyptian structures and recalls the construction in Mel Gibson's disastrous adventure into Mayan culture, the dreadful "Apocalypto."

Although the movie takes place somewhere in the Stone Age, the invading horsemen wield steel swords and spears and even employ metal in their handcuffs, demonstrating mastery of a technology developed thousands of years in the future, a remarkable achievement even for motion pictures. In keeping with the multiplying absurdities of the rest of the movie, the Stone Age warriors, armed with wooden weapons, overcome their heavily armed opponents, who in addition to their steel blades, also fight with bow and arrow.

Obviously an expensive work, with an enormous cast, a wide range of locations, and some stunning cinematography, "10,000 BC" fails on just about every level - as film, as the epic its makers intend, and as exploration of the ancient past. The corny, melodramatic acting - no one in the cast behaves with the least bit of distinction - naturally must suffer against the background of enormous beasts and violent action, which means that, just like the usual Lucas or Spielberg flick, the picture must depend on its special effects. When those effects themselves demand an outrageous violation of history, not to speak of time and space, the whole enterprise becomes ridiculous; I'd rather watch Victor Mature battle dinosaurs and Raquel Welch run around in a brontosaurus bikini.