Nara Prefecture can easily be considered the historical heartland of sake. Far more than any other prefecture, historically and culturally, Nara is an extremely significant sake-brewing locale.
During the eighth century, the city of Nara was still the capital of Japan. In 689, the Imperial Palace established a brewing department within its walls called sake no kami. It is technically difficult to pinpoint just when sake became sake. But, by this time, it was certainly close to what we know today.
Eventually sake brewing moved from the palace to temples and shrines, and then again to the common folk. So technically advanced was the sake of Nara that even into the Muromachi Period (1392-1573) the term Nara-zake signified great sake.