I've seen some interesting theories floating around on other fourms that the Uzumaki clan weren't just killed off by the other villages but were really killed as a part of Madara's plan. Now the counter argument to this is how was Madara able to move around when he was probably old by this time but lets remember this:
The Mist was already known as 'the bloody mist' before Obito controlled the Mizukage which I think is Madara's doing. Now what would Madara have to gain from this? Well think about it, the Uzumakis were known for their sealing techniques and being feared for it by other villages they were destroyed. Now I think that the destruction of the Whirlpool village was committed by the Mist Village. They had the Sanbi at the time which was their largest and most dangerous war potential so the Whirlpool Village, being allies of the Leaf would have sealed the Sanbi away to protect Konoha. Madara as Mizukage could have convinced the Mist higher ups that the Uzumakis were a danger to the Mist village by sealing the Sanbi when in fact he was really more concerned about them sealing the Juubi in the future thus destroying all hope of achieving Tsuki no me.
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The Mist was already known as 'the bloody mist' before Obito controlled the Mizukage which I think is Madara's doing. Now what would Madara have to gain from this? Well think about it, the Uzumakis were known for their sealing techniques and being feared for it by other villages they were destroyed. Now I think that the destruction of the Whirlpool village was committed by the Mist Village. They had the Sanbi at the time which was their largest and most dangerous war potential so the Whirlpool Village, being allies of the Leaf would have sealed the Sanbi away to protect Konoha. Madara as Mizukage could have convinced the Mist higher ups that the Uzumakis were a danger to the Mist village by sealing the Sanbi when in fact he was really more concerned about them sealing the Juubi in the future thus destroying all hope of achieving Tsuki no me.