Board Thread:Wiki Discussions/@comment-1512913-20140521221412/@comment-3568954-20140523085557

Elveonora wrote: Hagoromo's Rinnegan split into Ashura and Indra's chakras ("body" and Sharingan) That alone is enough, since there being 2 Sharingans is impossible. It can't go Sharingan > Rinnegan > Sharingan, because the Rinnegan is the original stage of Sharingan. The antagonists haven't been attempting to create a new doujutsu, they recreate the original one. Rinnegan was already there before the Sharingan. The Sharingan is an evolution of the Rinnegan, by re-merging the sons' powers, the Sharingan essentially devolves back into its original form, the Rinnegan.

The sharingan came first they say this when they say that kaguya had the byakugan and the sharingan hagoromo doesn't say she had the buyakugan sharingan and Rinnegan further more the Rinnegan is the power Hagoromo inherited from Kaguya but in his own body so its appearance is different. he was likely born with a sharingan and it evolved into the Rinnegan. the Rinnegan is simply a mutation of the Sharingan when Indra was born he had the power he got from his father but in its original form(the Sharingan)