Nasus and his interaction with Amumu

This has probably been brought up before, but wouldn't have at least a passing knowledge of what happened to before his death and following resurrection? Considering that his title is Curator of the Sands, as well as being a human that was ascended before 's betrayal, death, and rebirth? At least getting a time line of when Amumu had died would be nice for digging into the lore, so that we can see just what era of Shurima he is meant to represent, considering that we have two such beings in the Freljord in and , and another with an unstable location and plan in .