When was ninjutsu invented not Masashi Kishimoto's version but actual ninjutsu?

Answer 1

i have done reasonable research on this topic some say it was made for self defense for farmers against samauri cold hard truth it traces back to India. But it actually became ninjutsu by ninjas ninjutsu (art of the ninja). it was invented back when Japan was ruled by daimyos. to kill! ninjas where not the good guys unless you hired them. the year it was invented is uncertain but it was made before midevil japan around 6th century a.d. and is never finished because it is every Martial Arts combined ....... the seventh hall of death is espionage or the aart of learning aka. the never ending hall