As you know Madara died seconds after awakening Rinnegan, yet we see him as an old man with Obito ? Why is he still alive?
To some up things ...
Hashirama defeats Madara > Madara awakens Rinnegan > Madara dies (all happened on the same day) > ????? revives Madara > Nagato is given Rinnegan > Akatsuki is formed > Madara saves Obito > Madara meets Kisame > Madara meets Itachi > Madara Dies again > This time Madara is revived by Kabuto
So thats twice hes revived? first time by a mystery man, is that order correct? My theory is that either Orochumaru or Kakuzu revived him before the 3rd war!