What is the importance of the Rasulum Leaves in the novel, Earthborn?

The Rasulum Leaves are the inscribed gold leaves found by King Ilihiak of the Zenifi when their people traversed the edges of the Gornaya. They contain an unknown language similar to the Coriantumr stone in the Darkemba and, through the course of the story, it is revealed is actually an account of a previous human settlement on Earth, the Rasulum tribe.