Board Thread:Naruto Discussions/@comment-12509038-20140902203600/@comment-4688597-20140908084145

That means he used the Outer Path and the Deva Path, which are apart of the six paths technique, doesn't matter how many. Not to mention those are Madaras rinnegan in his eye sockets. Also, it even says so on the article, because no one else who awakened their own rinnegan got the Six Paths technique. Hence his name: Sage of the Six Paths.