Board Thread:Theories and Speculation/@comment-1872728-20160229033316/@comment-27660682-20160302063101

The senju were said to be equals or even stronger than the uchiha clan though. So they must have have had something that allows them to compete with the sharingan outside of the wood release. Tobirama stomped izuna and hashirama stomped madara, twice. And those are just the leaders of each respecive clan and both wins went to senju.