Several other regions of the world have extremely rich traditions, oral traditions of literature, predating by centuries events of the Middle East.
Secondly, I think it's a fair assumption that there were oral traditions long before the invention of writing, but this is likely true for people living in the Middle East, or elsewhere. And as a sidenote, how can you prove the existence of extremely rich oral traditions?
The brahman was the reciter of hymns from the atharvaveda who was largely silent and observes the procedures and uses Atharvaveda mantras to 'heal' it when mistakes have been made.
So at least when it comes to accuracy, it was very resilient.
I think my history teacher also mentioned something similar for the Jewish priesthood.
It is just that we don't know anything about oral traditions thousands of years ago, since they leave no archeological trace. What we can know about is what is written down on durable material, and Sumer happens to have some of the very oldest surviving writing.
Stories are probably as old as language, but this is pure speculation.
Isn't that contradictory? You have oral traditions, and then you have literature ("literature" means written work)