Board Thread:Naruto Discussions/@comment-29393962-20161111215453/@comment-734582-20170114095308

Georgio722 wrote: I've always thought that you needed something to manifest the Rinengan from (ie. upgrade the Sharingan), I guess Rinnegan is something that can be manifested from chakra alone. But if this also applies to SPSM, then what determines the manifested ability to be the Rinnegan for Madara? I'm not saying it makes no sense. I can completely understand the reasoning why people think that a dojutsu is needed for a stronger dojutsu. But sasuke's eye is irrefutable proof that Rinnegan and Sharingan are separate dojutsu. Ergo, you don't need Sharingan.

SPSM seems to require some prerequisite sage mode (Naruto has sage mode, Obito/Madara had juubi). Madara lacked a Sage Mode in his first life that would've given him SPSM. If Hashirama got Madara's cells, he would've awakened SPSM and eventually rinnegan.