Board Thread:Naruto Discussions/@comment-28861328-20140618060932/@comment-5936871-20140628022637

Darhumphump wrote: just because there aren't any in mention doesn't mean they died out, how many Sarutobi clan members do you know of, or Shamura clan members?

Well yes, but considering the fact that the Senju are always referred to in past tense, and the fact that they aren't one of the four noble clans of the Leaf, implies they're gone for an unknown reason. Especially since the Senju were the strongest clan in the world, and not a single Senju clan member (Except possibly Tsunade) is alive in the Leaf today. No one even has the last name "Senju" at all. So either they died out somehow or Kishi just completely forgot about them and didn't think of a good reason for them to disappear. But they're clearly no longer around.