This unit has been thought to be used since the Chinese prehistoric period. Length from the thumb to the tip of the middle finger of an opened hand. The Chinese character of “shaku” (尺) resembles that shape. In the Han dynasty (China, 206 BCE-220 CE), the length of a flute that produces a pitch called “huangzhong” (the first note of the ancient chromatic scale) was set as the yardstick. Very artistic!