What happened to all the people with Senju last names?


In Naruto, the Uchiha clan was wiped out by Itachi, which makes sense why you
don't see many Uchihas in the show. However, why do I hardly see anyone anyone
in the show with the last name of Senju? The last time I recalled, they
weren't wiped out by anything. What's up with that?

Note: I know that the Narutopedia page for the [Senju
Clan](http://naruto.wikia.com/wiki/Senju_Clan) gives a short explanation, but
I would like further elaboration.

