Board Thread:Theories and Speculation/@comment-25643824-20161215211806/@comment-681696-20161216023049

Yes, Madara thought that just mixing Senju cells with Uchiha cells was enough to get the rinnegan.

However according to Hagoromo mixing Asura and Indra chakra to recreate his chakra was the real requirement for the rinnegan.

Plus if just mixing the Senju and Uchiha bloodline was all that was required then wouldn't Black Zetsu have encouraged the Senju and Uchiha make peace and to merge into one clan instead of manipulating Asura and Indra transmigrations.