The Sasaki Clan

The Sasaki Clan was the intermediary clan in between the Senju Clan, and the Uchiha. When one side called the Uchiha, the opposition would call the Senju and vise versa, but the only way to break the stalemate was calling a multitude of different clans, or calling just one, the Sasaki Clan. When this clan was called both parties became desperate as they were truly neutral, they'd go agaisnt both Uchiha and Senju openly, they however were not decents of Hagoromo Otsutsuki nor Hamura Otsutsuki, they were purely human, thats is what made them terrifying. They werent bound by any curse nor bloodline, they were a clan of warriors and conquerors, they had no bloodline, nor special physical constitution, nor talent. They had in fact just one thing, an unbreakable will of survival, and a well of potential, both sides feared fighting, after all nobody wants to fight a fearless warrior on the verge of death.