@DWFII was watching one of those wild bush people of Alaska type shows and they took fresh hide and soaked it in a barrel with water and fireplace ashes....I forget how long they left it but they basically said it was what the used for raw hide...for wrapping tools handles with etc. Is that literally the most basic steps in leather production? Something that would date back to beginning of leather usage? Does stretching and air drying hide work as well?
I've read numerous accounts but they all seem to be so nebulous or far-fetched, all I can do is speculate...I wasn't around then.
Rawhide that is air dried will be brittle...we used to call them "flint hides." I suspect the ashes are used to slip the hair. When the rawhide is wet it may be stretched over handles, drum heads, saddle trees, etc. and as it dries it will shrink and become very stiff...and extremely strong.
It's hard to tell how leather tanning was discovered. Rubbing greases--brains--into rawhide and smoking it (is a well known method of preserving the hide. Probably a logical next step from smoking meat or fish.
Although that doesn't soften the hide--that requires a manual breaking down..."staking"...of the hide.
I always figured that perhaps the first intimations of vegetable tanning might have been the discovery that animals or people who died in ancient forest pools or peat bogs (wasn't Otzi found in a peat bog?) seemed to be better preserved.
I don't think we'll ever know.