Ok, for a while now i have noticed that Hashirama Senju's younger brothers name sounds a lot like a combination between Hashirama and Obito. Now, Since Obito is also known as Tobi this very much supports my theory. Which goes as follows. I believe that the Naruto and Dragon Ball universe are one in the same and that the events of Dragon Ball are in a semi-distant future. This would suggest that jutsu such as the rasengan are more of a primative version of the Kamehameha Wave. But more on that another time.

Since they are in the same universe the people in naruto getting a hold of the fusion dance (or in that time would have been known as the fusion jutsu) is not entirely unlikely. This is also supported by the use of the transportation technique or the instant transmission being a way that the race that originally taught Goku the Fusion dance teaching others on earth the same.

Now you may be wondering among other things why would they not have just gone back to being Obito and Hashirama. Well thats simple! Batara Earings! These earings allow to people to fuse together however this type of fusion is not something that can be easily undone and would have caused them to stay fused. It is also well known that both fusion by batara earings and dance can cause a different sort of personality to emerge.

Now the next question may be ''Well how did those two of all people fuse and they were different ages?''. Well my good friends it is simple. The Yamanaka clan were of course around in those days and it is not entirely unlikely that one of them being Obito's accomplice from present times was to use the mind control jutsu to make someone who posessed the dragon balls at this time give them to Obito. Using this he was able to wish to go back in time and not age untill a certain time as to whenever it suited him.

This part is where it gets complicated. Obito then found another Yamanaka and explained to them that he was from the future and of course they did not believe him and they thought he was a spy from another village. This Was disproven when he showed them his sharingan. He explained about the dragon balls and proved he was from the future by telling them events that would happen over the course of the next few months. These of course came true. He then was able to Get close enough as to use his Kamui to transport Hashiramas body that Madara had not used for his own gain to him and began the strange process of which is unknown. What is unknown is how exactly he fused whether it be batara earings or dance.

At this point Obito went into hiding with his accomplice who perished over time as they were not immune to ageing like Obito was due to the wish he had made earlier. He was also now who we know as Tobirama and had used the Skills of his Yamanaka friend which he had also fused with to mind control everyone into thinking he had existed for years . This of course worked and he had even used the limited Tsukuyome to invent a small future in which he faught and helped the village, This would cover up any loose he may have forgotten to fix or hide.

After time however and a talk with the near dead Madara and avoiding his younger self, Obito was able to find a way to un-seal himself from the Yamanaka and Hashirama as they were causing him to age quicker due to them being nearly dead when fusing. This unfortunately meant he lost the Yamanaka Kekke-Genkai and was unable to use Mind control or mind transfer jutsu. He did however now have Senju dna which is why he was able to achieve the Rinnegan in the end!

But hey guys, its not just a theory... But a Game Theory! But an Anime Theory!