So the man in the mask unleashed the nine-tails with power of the sharingan. This caused it to go on a rampage that the third and fourth hokage had to divert their attention to, leaving kushina vulnerable. To save the village, the tailed beast had to be sealed inside of naruto. After the attack, the village elders were immediately suspicious of the uchiha clan, and investigated using information gathered by itachi. The senju-aligned elders were ready to wipe out the rival portion of the clan. Now, do you remember when I mentioned somebody called "madara"?