There was a greate legend that, in uchiha clan or kisai clan,a child with both clan's chikara will born in one of these clans and wrote his legends Uchiha and Kisai clans were friend clans but during 2nd Greate Ninja War,a shionbi name Uchiha Hisao betray his own clan and blame it to clans were seeking for revenage as a result many people died the leader of kisai clan decided to go from going from leaf he said that "We will come back for revenge so be ready for next Greate Ninja War.
Kisai made their new village called"Hidden Warrior Village"some clans help kisai to make thier own other shinobi was allowed to enter that was hidden behind the greate Hazumi waterfall.