From Shiro Kuma by kumafr

- First, what we call the “Japanese martial arts” developed out of necessity. Between the Heian period (1185), and the forced peace at Sekigahara battle (1600), Japan was at war. (1)
- Second, Japanese people were small. The founders of Gendai Budō (Jūdō, Aikidō, Karatedō) were all three, around 150cm in height! (2) We can surmise that was the case for the majority of the Japanese people.
- Third, in the Kanejaku system of measures, the central size is the Ken (6 Shaku, app. 182 cm), and every building in Japan follows this system of length. (3) Shakkanhō is the name of this global system of measures. (4)

- A Bō is six shaku + 20%
- A Jō is four shaku + 20%
- A Hanbō is three shaku + 20%
