Re: What happened to the Senju Clan???
Senju clan- Strongest clan of the times, no unique traits, shinobi skilled in all aspects of a ninja : Genjutsu/ninjutsu/Taijutsu and etc.
Uzumaki clan - separated on an island, and specialized solely in fuinjutsu
Uchiha clan - Known for their eyes and specialized in the sharingan.
If you look at all the clans in the leaf, they specialize in specific things.
Yamanaka - mind jutsus
Nara - Shadow
Akamichi - "fat" jutsu specialty or "size"
aburame - insects
Hyuuga - Byakugan
Sarutobi - Katon is unique to them
Inuzuka - Dogs
All these clans have a specific trait.. Senju did not (even some uchiha defected to the Senju clan). When you don't have a specific trait to define out your clan it is bound to fade away once it starts to merge in with other clans. I mean hell maybe some uchiha married senju later on. Who the hell knows. But the Senju clan simply faded away. Tsunade is the only known senju, because of her Grandfather.. who was the leader of the senju.
But is Senju BLOOD still alive ? Yes..some people in Konoha , and i believe the "family names" like Hatake and Namikaze and Haruno relate tot he senju. And lets not forget the main character himself has Senju blood inside of him through his mother.