Soboshu is a collective term referring to Japanese sake brewed in major temples from the Heian period to Edo period. It was highly valued for its high quality.
Until the early Heian period the Imperial Court had a department called Mikinotsukasa (Sake brewing) and brewed sake inside the court, but with the declination of kanga (government office), the technique and staff for sake brewing ran out of the court until major temples in many provinces including the Provinces of Yamato and Kawachi began to play a major part in commercial sake brewing.
In those days, sake brewing was what is now called leading-edge biotechnology and major temples were in the following situations which were so favorable as to make it possible for them to be entrusted with and take charge of such state-of-the-art technology.
Economic power - In those days, when major commercial capital had not emerged yet, major temples received the biggest capital in the form of rice acquired in plenty from their vast shoen (manor in medieval Japan) as well as of abundant donation from nobles.
Manpower - There was a great abundance of energetic workers who did not know what to do with their strength, such as ascetic monks and monk-soldiers, in major temples.
Power of information - Major temples were the first to learn knowledge which had been brought to Japan by intellectuals including foreign monks as well as monks who had joined Japanese envoys to Sui and Tong Dynasties China and studied abroad. Such knowledge included farming methods and brewing technologies concerning sake brewing.
Power of the environment - As the highest educational institutions of those days, major temples enjoyed academic time and space which enabled investigation, experiment and improvement of new information and knowledge without being bothered by worldly desires.
Political power - Major temples of those days were granted what is now called extra territorial rights and under the protection of the Imperial Court they were privileged enough to develop industries which could not have been developed in town. Furthermore, thanks to the extra territorial rights, major temples were the center of what is now called "brain gain" or concentration of human resources, because many prodigies who were so unique that they were treated as outlaws by the general public, as well as influential people who had lost in power struggles, poured into such temples (asylum) and used their networks with other provinces.
Situations in other countries
In fact, from the perspective of world history, Japan is not unique in that major temples play a primary role in the brewing industry during a certain historical period, especially in the Heian period or medieval times. As seen in the visible examples of wine and champagne made by monasteries of Benedictine Order as well as of beer made by Trappist Monasteries in Europe, many civilizations have a period in which religious power leads the brewing industry for reasons similar to those stated above.
Of numerous kinds of soboshu, 'Nanto-Morohaku' made by temples in Nara retained a high reputation for a long time, until the Muromachi period. Outside Nara, "Kanshinji shu" and "Amanosake" (made by Kongo-ji Temple [Kawachinagano City]) in Kawachi, "Hogen shu" in Echizen (Hogen-ji Temple) and "Hyakusaiji sake" in Omi were the most famous.
The brewing industry temporarily declined due to the Genpei War at the end of the Heian period, but as money economy prevailed in the Kamakura period, soboshu was highly valued in the market again. Sake breweries developed in Kyoto City but soboshu, made by temples which quietly continued brewing sake without being bothered by worldly complication, was more highly-esteemed as merchants in town began to fight over the market as in the case of Bunan no Koji Sodo (Riot caused by rice malt sellers in the Bunan era). In this way, soboshu reached its peak in the early Muromachi period.
In the course of time, major temples began to be harshly suppressed by busho (Japanese military commanders) in the Sengoku period as typified by Nobunaga ODA, because such military commanders feared above-stated powers and interests held by the temples, regarding them as rival forces. That is why the history of soboshu ended there. However, the high-level technique and knowledge concerning soboshu were passed on to breweries and schools of toji (sake brewing experts) in various areas, and even documented in a hidensho (book of secrets) such as "Domoshuzoki (a technical book on sake brewing)" in the early Edo period.