Long long time ago an advanced cast civilization created nanobot network. However now it had fallen and people migrated away from the land. By the time they come back to land of their ancestors most of the lore was lost and the ruins of the old world was covered by earth. Sure, they are able to dig up some artifacts, but with their knowledge (high Middle Ages) all they have is strange green plates covered in mystical writings etc.
However they discovered that they are able to perform magic if they speak in ancient tongue. What really happens is that nanobot networks is recognizing commands and performing them.
- Nanobots are coded by genetic patterns. The larger portion of network recognizes the pattern the more potent the magician is as nanobots are destroyed (run out of energy) after doing things - though they replenish over time. However part of network is broken and there was natural drift so not everyone is magician.
- Depending on the type of command various access levels are granted. Creating food or playing audiobook are not a big deal. Putting a sedative into someone ('sleep' spell) requires nanobots to recognize someone to be from law enforcement lineage. Creating a fireball requires to have a 'license to kill' lineage etc.
- Most common things (create food) are simple commands which can be spoken but nanobots can be programmed. People skilled in programming them are not necessarily those who are able to perform them (though it helps). Such programs can be stored and invoked by command by person storing them.
How would it transform the formation of societies which migrated back to such land? How much could be recovered from ancient audiobooks assuming they have no means to distinguish fiction from non-fiction and they have no index - and no idea what a nanobot is or computer or PCB etc.?