Board Thread:Theories and Speculation/@comment-3965545-20160511191323/@comment-5936871-20160512200950

Black Zetsu said "Indra and Uchiha... Asura and Senju... As they disputed and battled with each other, the desire for and pursuit of chakra was created... and since then, I approached both families' successors over and over... each time, trying to awaken the Rinnegan failing." though this may be different in another translation. Anyway, Black Zetsu confirmed that Indra and Asura only incarnate themselves into those directly descended from their lineage. He pretty much said that Naruto indirectly belonged to the Senju Clan due to being an Uzumaki. This, combined with Nagato being stated to have Senju lineage due to being Uzumaki would confirm that the Uzumaki are nothing more than red-haired Senju who branched off at some point and became their own clan.