@Riley @aparrish
Clay got so much use because it was all over the place in the riverbeds and marshes. It didn't really need to be processed, & scribes were trained in grabbing it & turning it into tablets.
Maybe the labor or amount of clay necessary became large enough to be recorded for the mass-produced tablets.
@enkiv2 @Riley that makes sense. my thought was that sometimes the various empires were large and might have included cities that weren't close enough to riverbeds and marshes for tablets to be easily created on-the-fly? (but really I'm just trying to figure out what would have been the first writing that referred to its own medium and this seemed like a plausible scenario)