Ninshū

is the religion and the peaceful precursor of modern ninjutsu created by Hagoromo Ōtsutsuki, the first one to understand and teach the mystery of chakra. The teachings of ninshū were meant to give people a better understanding of themselves, as well as others, and lead the world into an era of peace. Ninshū would eventually come to be known as ninjutsu, a more weaponised version of the Sage's teachings.

Hagoromo exemplified his teachings by distributing chakra meant to "connect" people's spiritual energies with one another. It would allow people to understand each other without communication and pray for one another's safety. After being passed over as the successor of ninshū over his brother, and subsequently manipulated by Black Zetsu, Indra Ōtsutsuki was the first to weaponise it into ninjutsu.

Others followed his footsteps, using chakra to connect their inner spiritual and physical energies together instead of each other. It was Hagoromo's belief that no one's chakra should be so much greater than any other. If the power is accumulated into one person, then it increases the possibility that the person will become arrogant and desire even greater power. In the end, they ended up using their chakra in battle, just as Hagoromo's mother Kaguya did.

Trivia

 * Naruto Uzumaki distributing his and Kurama's chakra to connect and protect his fellow shinobi during the Fourth Shinobi World War bears many similarities to Hagoromo's original intent by originally distributing chakra as a whole.
 * Killer B prominently displays something similar to Hagoromo's intended use of chakra in his ability interpret the hearts of others. Through a simple fist bump, he can read someone's thoughts and memories, transmit his own, and enter their mental landscape. This lets him recognise even complete strangers and how important they are to someone he knows.
 * This ability was foreshadowed by Sasuke Uchiha, who mentioned that high-level ninja could read the thoughts and intentions of others through an exchange of blows.
 * In The Last: Naruto the Movie, when Iruka asks his pupils who they want to spend their last day on earth with, a sentence that is likely one of the teachings of Hagoromo's ninshū can be seen. It says and is signed by the Sage of Six Paths.