I just read chapter 600 and ... come ON! He decided to destroy the world for a girl! :sy:
And more than half of it was flashbacks that we had already seen.
But it did tell us that Madara and Obito know each other. So here is my theory:
We know that Madara didn't die in his battle with Hashirama. And he got his hands on Hashiramas DNA. So I think he is the one who created Zetsu and in the same way he saved Obito who had been crushed under those rocks and trained him.
Then using Rin's death he convinced Obito that Konoha has to be destroyed. That's why obito attacked Konoha 16 years ago. But I think Obito came up with "Eye of the Moon" himself.
Also:
Using his own Uchiha blood and Hashiramas DNA, Madara created rinnegan. He gave it to Obito and Obito gave it to Nagato.
Obito's left eye was still blind when he attacked Konoha. That's why he used to wear that mask with one hole.
When Obito told Susuke about the Uchiha massacre, what he said about his past was actually what Madara had told him.