Twelve years before the events at the focus of the series, the nine-tailed demon fox attacked Konohagakure. It was a powerful demon indeed; a single swing of one of its nine tails would raise tsunamis and flatten mountains. It raised chaos and slaughtered many people, until the leader of the Leaf Village - the Fourth Hokage - defeated it by sacrificing his own life to seal the demon inside a newly-born child, whose origins are as yet unknown. That child's name was Naruto Uzumaki.
Here's the link to Naruto chapters 187 + : http://stoptazmo.com/manga-series/naruto/
Note: The anime equivalent of Naruto Shippuuden begins at chapter 245.
