Lecture No.1: Communication network system in Ancient Japan - Organization of "Tobuhi" and Ancient Japanese Society (2nd term)
Communication network system in Ancient Japan - Organization of "Tobuhi" and Ancient Japanese Society (summary)
Lecturer: Akira Yamanaka
Generally speaking, intelligence activity can be recognized as the main duties of ninja.
In Ancient Japan there was a law and system for communication, called "Tobuhi", because "Ninja" did not exist in ancient Japan. Tobuhi was a method with a signal fire for sending emergency messages about invasion by enemies.
According to regulations found in the "Engishiki" two signal fires were to be set once the enemy was found within the territories of Dazaifu, and three signal fires meant that the amount of the enemy ships were over 200.
In Japan Tobuhi were set in highland villages, which were ruins of the Yayoi Period. One could assume that the villages were located in highland for their ideal place to use signal fire as a part of their communication network. Another typical style of ruins in highland was called Korean-type mountaintop castle. After the defeat in war at Hakusukinoe against the Tang and Silla allied forces, Prince Naka no Oe (later Emperor Tenji) and his government built a series of impregnable mountaintop castles with massive walls in the area from the northern part of Kyushu to the coasts of the Seto Inland Sea. Those castles were built for preparing their reprisal, for setting signal fire platforms in case of emergencies, and also for food reservation, in case they had to hold the castles.
In the Nara period, the regulations for arranging Tobuhis were defined in the Gunboryo (the Statue on Military Defense), which was modeled after the system of the Tang dynasty of China. Accoridng to the laws, every Tobuhi should be positioned in intervals of about 20 kilometers (40-ri) at any appropriate place. For sending messages, people emitted white smoke during daytime and flames after dark.
The "Izumo no kuni fudoki" and also other Fudokis (description of regional climate, culture, etc.) show us clearly that there was a Tobuhi-system and that the Japanese nation under the Ritsuryo codes had its emergency information transfer network throughout Japan by way of Tobuhi. As a good example, we can find the platforms for Tobuhi in the ruin of Tobiyama-castle (in Utsunomiya City) which was, if it refers to the castle built with a space of 50 meters in between as its regulation. Also a clay pot was found with "Houka" written on it.
Tobiyama castle was known as a residence castle of the Houga clan and their name originated the Tobuhi system in the Nara Era.
Tobuhi, signal fire, its history goes hand in hand with the history of war. Lots of ancient castles had some platforms on their walls for setting fire signal as part of their defense system. For example, the Great Wall of the Chinese Emperor Shin Huang-ti, built on the frontier to protect against invasions by northern equestrian tribes, and also Hadrian's Wall for defense against the Scott
At the Jinshin War, Prince Oama (later Emperor Tenmu) ordered his right‐hand men, Murakuni Oyori, Mugetsu Kimihiro, Wanibenoomi Kimite to secretly prepare for war. They can be recognized as origin of "Ninja" because of their intelligence activities.
