I think it might be possible to... over-state that.
Im sure that in some regions many of these oral histories are preserved, but in others they've sadly been lost to time. In my region there aren't any youth spending their days learning these histories, and I doubt there have been for the last 5 or 6 decades really.
Even Aboroginal place names are very unreliable.
I think cave art is also quite intimate. Like the hand prints and stencils are very human.