Chakra Theory

[Assertn]

ha....thats nothing.....
a bunch of the different characters themselves are based on mythologies as well.....like oro, jiraiya, tsunade....and i believe sasuke was some legendary ninja as well
also, ninjutsu is actually a martial art, and the use of hand seals is based on ancient stuff as well

[nests]

Also that pill that kabuto uses was an actual pill that was suppose to substitude entire meals.
but there is no actual records of any of them just rumors since ninja stuff was suppost to be secret

[Tofu #2]

Yup he was a legendary ninja alright. Sasuke Sarutobi. The ranks of the ninjas (Genin, Chunnin, Jounin) are also based on ninja stuff.