Jeff Rients is talking about his Imperishable Flame campaign setting over on his blog. Among other things it takes place at the dawn of written history. This is was a time when the earliest civilization in the Nile River Valley, the Fertile Crescent and Indus River Valley were beginning to develop. The world outside these realms were mostly in the midst of the Neolithic Era or new stone age.
This was not a time of cavemen and spear. It was a landscape of villages, and the first pastoral tribes. Yes their weapons and tools were still made of flint but by this point it was supplemented by pottery, and weaving. With the occasional metal ornament made of copper, silver, or gold (all mallable metals easily handled over an open fire). In Europe the first megalithic structures were being built and a Venus cult of the Earth Mother dominated much of the continent.
In my Majestic Wilderlands Campaign I have several additional classes that would work in this settling. And some thoughts on existing classes.
These would be a product of the growing literacy and religious sophistication of the cities and would not be suited for the Neolithic instead
This is similar to a cleric but able only to cast spells through rituals.
This is similar to a magic user but only able to cast spells through rituals.
You can cast any spells you memorized it takes 10 minutes plus 1 gp times the spell level squared. Not that the gold piece is an abstract unit in this case. Perhaps something like hide, shells or some other suitable unit in it's place. Anyway the intent is that these guys spend a lot of time gather the stuff they need to cast spells.
The technological progression of magic would go like this.
Memorization of Rituals the number of which is the same as the normal spell chart.
Able to cast rituals from a ritual book with the max level of ritual allowed the same as the max spell level if the character was a normal spell using class.
Able to cast any spells normally but only a vary small number and a limited choice (like D20's sorcerer class)
Finally the normal spellcasting of D&D magic
The later on the addition of the Shield of Magic
A couple of my Rogue classes would work as well.
The tribal bullies using brute strength and not skill to get their way
Wandering the Neolithic landscape bartering between tribes. Plus important in forging alliances and peace between tribes with deals involving goats, sheep, or cattle.
If you back further to around 5,000 BC you still have the Neolithic landscape but the regions of the early civilizations are places that are very prosperous and densely populated compared to more other regions.