I have no proof on hand but I have seen for instance a documentary on the French German station ARTE tv where they featured a kind of crazy dude who have gone through more or less every oral story of a tribe, the western world actually have written down. Then he started to compare and traced bits and pieces and this is really crazy who many parallels you will find. He then together with anthropologist estimated how old these stories might could be, based on travels and migrations like those of the caretakers...