Talk about a late bloomer. From its location in the northeastern corner of Honshu, Iwate Prefecture exerts a tremendous influence on the sake world. Yet, sake was not even produced there on any real scale until well after 1678, long after Nada, Itami and Kyoto were well into their sake-brewing heyday.
What happened in 1678? One Murai Gonbei, an Omi shonin (traveling Kansai businessman) settled in Iwate. With him he schlepped the knowledge of brewing "sumi-zake," filtered sake, which was for all intents and purposes sake as we know it today, albeit a bit rougher. He taught this to the local farmers, who picked up the new hobby with enthusiasm.
Also, as with everywhere else in Japan, the samurai leaders of the area had to spend every other year in Edo. This resulted in huge throngs of people moving down into the Kanto region and into Edo. It was through this mass migration that much more sake-brewing technology was picked up and taken back to Iwate. There, it was refined and localized.