[@Willy Vereb]I don't see much problem with it. It's been a while, it's fair to say that human records of them, if they even had any, were lost over time. Or the damage to Mars caused a great loss of most traces of them. It's easy to explain why information is lacking, and even your NS says the non-Martians don't even have much left from them despite being directly descended from them. If someone wants to use it then it's fine, but if not then they're easily forgotten.