The information I got from this chapter

[uchihamad]

1. Sage of six path's brother don't have much to share to the story . He might have died after fighting against juubi or simply let Hagoromo to take the position of successor i.e Hagoromo is the elder brother . So sage of six path's elder brother also believed in this tradition and he thought after Hagormo he will become the successor.

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2. The shocking truth might be that juubi is the source of evil or it is the final vilain. Sasuke might have already knew the story or all the facts about so6p and juubi from the uchiha tablet in Nakano shrine. That's why he wanted to burn them down .

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[uzmakinaruto]

if sasuke knew about that then why he still wanted to know about shinobi village and all bullshit....
That also means that itachi knew about all this?

tablet didnt share that much details

 

[BigGuns Reloaded]

makes sense as to y the tablet was shown and to y sasuke went there