Arms and Equipment guide has a good treatment of differing arms and armor at differing time periods / development levels -- covering the stone age, bronze age, dark ages, and crusades, specifically..
And both A&Eq and the 3.0 DMG have rules for Stone and Bone weapons (-2 to hit and damage, minimum damage still 1, hardness/hitpoin ts 8/15 for stone and 6/10 for bone).
If you're talking true, live-in-grass-huts style primitives, the A&Eq Guide lists the following weapons for the Stone Age (all are common except the whip): Club, Dagger, Dart, Handaxe, JAvelin, Quarterstaff, Shortbow, Shortspear, Sling, Whip.
For more-advanced primitives, you could go bronze age (bronze is -1 to hit and dsamage (minimum dmage 1), hardness 9, 20hp/inch), the list adds: throwing axe, battleaxe, gauntlet, spiked gauntlet, greataxe, greatclub, light lance, longbow, longspear, longsword, mace (light or heavy), net, composite shortbow, sickle, shotsword, trident, and warhammer as common weapons; flail (light or heavy), kama, and nunchaku as uncommon weapons, and drops the sling entirely.
At the dark ages or crusades level, we're talking pretty much, D&D standard between the two of 'em.
Note that things not listed are only "not usually found in this time period" ... there's no hard-and-fast rule. If you want a bunch of folks with stone warhammers ... go for it. A warhammer isn't that difficult a tool to envision, it's basically an advanced club ... ^_^