Board Thread:Naruto Discussions/@comment-25139119-20140905185119/@comment-4271790-20140905190105

In chapter 670, Hagoromo stated "we fought against the physical incarnation of the sacred tree, the Ten-Tails" which was Kaguya, "...and sealed it within ourselves" (which was shown to be sealed in just Hagoromo in the raws). Just like Hagoromo said, what happened was they fought the Ten-Tails and then sealed it within Hagoromo.