I am working on a D&D campaign setting which is set in a mid-to-late bronze age fantasy -- that is, some cultures are using primitive iron working techniques while more advanced cultures with better trade routes use bronze.

As a fantasy setting there is going to be magic, but I am struggling of thinking of ways to implement non-natural (arcane) magics in a way to make it feel more primitive or unknown. I can see many of the cultures using the natural magics of druidism and shamanism, but I feel that due to the lack of ease of communication and general organization between different cultures that the studying of arcane magics would still be rather primitive. A lot of the arcane magic is just rediscoveries of the techniques used by lost civilizations from many millennia before. There are no mage guilds, just hedge mages digging through through ancient ruins to uncover secrets they don't quite understand.

Anyways, my question is, what forms of arcane magic do you think would be likely in this setting?