The Valley of the End
We’ve first seen the Valley of the End during the Sasuke Retrieval Arc in Naruto Part 1. Naruto followed Sasuke and fought with him at this place. In the valley we noticed the statue and Kakashi gave a hint of its history.
While Sasuke and Naruto were fighting, Kakashi mentioned that it was the same place where two great warriors fought before. Seems like the two warriors were best friends and due to conflicting ideas, they battle to the end. The right statue was the First Hokage while the other is not mentioned or I just can’t remember who he was.
From the Manga chapter 370, Jiraiya mentioned about the fight between Uchiha Madara and the First Hokage. He said that the First Hokage defeated Madara but he doubts that Madara was killed totally. At the same chapter, Tobi was shown at the top of the left statue which gave me a hint that the second warrior was Uchiha Madara and Tobi is Madara. Uchiha Madara was shown as well in the said chapter and he looks like the statue.
[Naruto vs. Sasuke at the Valley of the End. After the jump.]

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September 15th, 2007 at 3:56 pm
[...] or closely related to him. Tobi was shown standing at the top of Madara’s statue at the Valley of the End, silently reminiscing their past fight. Seems to be. You might also like to read: 27ef Jiraiya [...]
September 21st, 2007 at 12:19 am
[...] event? The first time we saw Naruto transmute with the kyubii was when he fought with Sasuke at the Valley of the End. Kyubii’s sensed Naruto’s ask for help and lent him his chakra. Naruto looked [...]
September 24th, 2007 at 10:54 pm
when minato(the fourth) sealed the dark side of the kyuubi or thgrow it away . if this did happen it would most likely (the power of dark kyuu) would go somewhere but when this happened it most likely take a part of naruto at the same time the influx of chakra would probably create a hole in the space time continuem sending it to the past with a physical body and dark kyuu’s chakra thus the resemblance between pein and naruto because in a way pein is a part of naruto and the kyuubi
September 25th, 2007 at 2:35 am
Jiraiya mentioned on chapter 369 or 370 of the Manga that Minato only sealed the light side of the Kyuubi to his son which is Naruto. And it was done for a purpose. If your theory is correct that Pein has the dark side of the Kyuubi, then it would be Naruto vs. Pein. Thanks for dropping by.