You can go to nearly every part of the world and the people there will have at least some idea of what a ninja is.
Ninjas have so thoroughly permeated our culture and at some point we have to stop and wonder:
Where did ninjas originate from?
By the 12th-15th century, known as the Shinoku/Sengoku period, a class of warrior or fighter began to emerge and employ unconventional methodology.
Originally known as “Shinobi”, these people trained in martial arts and tactics that were drastically different from the norm of the era.
The first ninja clans arose from the Iga province in Japan during these turbulent times. Koga was the village in the Iga province that gave birth to the first ninjas. Eventually, multiple ninja clans arose and regularly battled one another in service to various Warlords.
Ninjas, or Shinobi, trained in a wide array of skills such as espionage, assassination, infiltration, stealth tactics, and more.
These ninjas were also utilized by engaging in psychological warfare to demoralize enemy troops or frustrate their lines of communication.
Daimyos, Warlords of the era, employed these stealthy Shinobi to complete tasks that Samurai found to be distasteful.
Many of the tasks or objectives created by these Warlords had drastic historical implications and influence over the outcomes of battles and skirmishes across Japan.
The most renowned piece of literature from the world of ninja was known as the Bansenshukai. This book was considered a training manual for ninjas. It covered many of the tactics, tools, and philosophies employed by ninjas.
One of the reasons current historians struggle to discover truth about ninjas and their way of life is due to the fact that they so often employed misinformation to maintain their secrecy. They would encourage false rumors and even start ones themselves to ensure that the truth about their locations, tactics, and techniques remained secret.
This level of secrecy has also been a factor as to why ninjas have attracted such interest over the years.