Board Thread:Theories and Speculation/@comment-5413572-20150114180437/@comment-26105571-20150213142419

Or it could be that you're all making this more complicated than it could possibly be. I'm a new user to this site but I have read this forum extensively since the beginning through an acquaintance who is no longer of this world, unfortunately.

Lets go over what is currently known: Now during this confrontation, the manga shows that Hagoromo was using Rinnegan and Hamura was using Byakugan. It could be that Hamura didn't achieve Tenseigan until at a later point in his life and decided that the Tenseigan was to powerful for single person to use and seperated the key to unlock it and passed it on to his Hyūga and Ōtsutsuki descendants to safe guard it until a time came for when it was necessary to achieve it.
 * Kaguya Ōtsutsuki is the first person to use chakra to godly capabilities
 * She birthed twin sons who inherited her power on a more diluted scale during their mother's span of pregnancy
 * Sometime during or after birth she became mad due to mental corruption from being the only being on the planet to use chakra
 * She then discovers her sons ability to use chakra and by that time the mental corruption has completely over-taken her mind
 * In an effort to reclaim what she believes is rightly hers, she merges herself together with the Shinju creating the Jūbi (a.k.a. the Ten-Tails)
 * Hagoromo and Hamura had no idea that the Jūbi was in fact their mother's incarnated state but believed it was the personification of her sins; the two then seal the Jūbi with the Rikudō—Chibaku Tensei technique but not before Kaguya manifests her will into what we know as Black Zetsu.