In my entry about Irizake I mentioned Hishio. Found in early Japanese literature (Manyoshu poetry anthology of Nara era) it had its own department in the imperial administration. A precious seasoning introduced from China, it evolved from a fermented fish or meat sauce into a fermented sauce based on cereals after the introduction of Buddhism in Japan (6th century), whose vegetarian diet was adopted or at least strongly influenced nobility. In Japan it was designated with the Chinese ideogram 醬 (jiang) which, in China, was referring to a fermented soybean paste. And indeed, soon miso paste would develop from Hishio in Japan, until it acquired its own written form 味噌 (miso) during the Heian period. Initially falling under a category of seasonings called Tamari, soy sauce emerged a few centuries later, acquiring its own name and ideograms in the 16th century: 醤油, read shoyu. It progressively replaced more difficult to conserve Irizake as well as other forms of Tamari or Hishio. The pictured Umebishio is a paste of Hishio, sour plums and Kombu seaweed, produced by Kyoto Ungetsu (京都雲月). Its strong umami, its saltiness balanced by the plum’s acidity is a treat on freshly steamed rice (or on finger’s tip!). It makes you drink more of that Kaze no Mori sake from Nara Prefecture!
Amongst my sources is the interesting unpublished History of soybeans and soyfood, by the Soyfoods centre in California