Medical Ninjutsu(Jak)

Medical Ninjutsu (医療忍術 literally meaning Medical Ninja Techniques) simply put are Ninjutsu based techniques which generally involving healing either ones self or someone else. To do this, the practitioner places their hands over the wounded area, and a beam of light will generate and begin healing the target; the beam of light will change colors depending on how much Chakra is being put into it, which will tell everyone how effective it's being. Although t his is the normal method for healing, there have been some, such as Hashirama Senju, who are able to simply look at a group of people and they're all healed immediately, as alluded to by Madara Uchiha when he was speaking with Tsunade Senju. The most advanced known technique for Medical Ninjutsu is known as Montonic Regeneration, created by Tsunade in order to obtain Medical Ninjutsu powers that are at least close to her grandfather, Hashirama.

Overview
The exact origin of Medical Ninjutsu remains largely unknow to this very day; however, due to it's direct connection to the ancient art of Ninshu practiced by Hagaromo the Sage, many believe that it is the oldest modern Ninjutsu art, and may in fact date back directly to the Sage himself, although it can't be proven or disproven, as nobody alive today has ever met him, and he's no longer alive to confirm or deny it.