Just a heads-up, I dunno if this is allowed, but /r/AskAnthropology might be a better place to ask this.
It's my experience that history generally ends where the paper-trail does. Writing and maintaining it generally requires a lot of resources , and even oratorically recording things generally requires keeping some guy around every generation whose main job is to remember the stories, which also requires some work that a society newly adopting iron might not have, with some exceptions.
Previous answer by u/wotan_weevil, which itself contains links to earlier answers.