In chapter 370 it was suggested that Uchiha Madara was the cause of Kyuubi summoning.I highly doubt it but it would sorta explain how the Bijuus came to be other than them just magically popping up out of nowhere. It would also open the question of who summon the rest of them.Maybe we might get to know about the ninjas that lived before the 1st Hokage,back to the point of this thread.Madara = Tobi why do I think so, Orochimaru had his body transfer jutsu,maybe Madara had his own jutsu that would keep him alive. The 3rd Hokage was a old man even before Naruto was born,and the day Naruto was born the Kyuubi was summoned and since Madara might have been the cause of his summoning it’s possible that he was alive back then.Even if Madara isn’t Tobi can you explain how Tobi has his powers.