The origin form of Miso, or soybean paste, is said to have existed in the Nara period -710-794-. In the Heian period, there were store selling Miso.
Miso is made from soybeans, which are steamed and mixed with salt and Koji-fermented rice, barley or beans-. It was made at temple in the Kamakura period-1185-1333-.
And in the end of civil war in the 15th and 16th century, it was used in rations for soldiers.
It was in the Muromachi period, when Miso became popular, as Soy sauce did among the general public.