Edo Tensei's need

[wildstorm]

so, its not madara's revival (as he didnt die till he met obito) , its neither izuna's revival, & not of hashirama for sure.....so only reason left for tobirama to develop edo-tensei, is to revive the senju clan, ie if they died during his time......I dont think they died during hiruzen or minato's reign.....
so I believe Senju disappearance & edo tensei development are related......

 

[Chibiusa]

It's possible

 

[MisterX]

never thought about the Senju disappearance

I mean the Uchiha we know but the Senju.. damn why hasn't this crossed my mind :X

 

[S A G E]

Maybe he revived one of his clansmen to investigate how they all died.

 

[Almighty Ra]

Good point but i honestly I thought it was to revive either Hashirama and their young brother Itama or possibly knowing how much death war brings he made to revive those lost in battle.I believe the senju aren't extinct but jus mixed with other clans.