A population of just under eight and a half thousand is a far cry from the late Heian era (around nine hundred years ago) and the Kamakura period when Hiraizumi was the home of the Hiraizumi Fujiwaras, the most powerful clan in Japan, and served as the de facto capital of an area that covered nearly one-third of the country. At that point the population was somewhere between fifty thousand and one hundred thousand, and the city’s cultural and political status almost rivalled the national capital, Kyoto.
The oldest structure in Hiraizumi seems to be Hakusan Shrine at the summit of Mount Kanzan (Barrier Mountain), described in 1334 as being seven hundred years old. The shrine has been rebuilt a number of times but its latest incarnation still stands in the same strategic location.
That strategic location, at the junction of the Kitakami and Koromo Rivers, was probably what prompted Fujiwara no Kiyohira to move his home to Mount Kanzan around 1100. The Koromo River was the traditional boundary between the Japanese heartland to the south and the northern Emishi peoples.
Japanese hunters, trappers, settlers and missionaries had been in contact with the Emishi since the early eighth century, with a Buddhist priest Gyōki establishing Kokuseki-ji Temple in the mountains east of the Kitakami River in 729. Military expeditions to subdue the Emishi were repelled in 776 and 787 but a Japanese scorched earth policy of burning crops and capturing and resettling women and children prompted the Emishi leaders Aterui and More to surrender in 802. They were subsequently beheaded.
It’s one thing to defeat your enemies but quite another to keep them subdued, and rather than ruling the newly-acquired territory directly it ended up as half a dozen semi-autonomous districts along the Kitakami River that eventually came under the control of a powerful Emishi clan, the Abe family. Semi-autonomous is the operative word here, and after Abe no Yoritoki refused to pay taxes to Kyoto, led raids south of the Koromo River and acted as if he was an independent ruler he obviously needed to be subdued.
The result was the Zenkunen or Early Nine-Years War (1050-1062) which saw the Abes defeated by Minamoto no Yoriyoshi and Kiyohara no Takenori and the six districts handed over to Kiyohara no Takenori. That didn’t work out either, and corruption resulted in the Gosannen or Latter Three Years' War (1083-1087).
Around thirteen years later, Fujiwara no Kiyohira moved to Hiraizumi, right on the former border, planning to rule an area stretching from the Shirakawa Barrier in the south to present day Aomori Prefecture in the north. His new base was located almost exactly in the centre of the Tōhoku region on the main road leading from Kyoto to the north (the Frontier Way).
Kiyohira built Chūson-ji at the top of the mountain and other pagodas, temples and gardens followed through Hiraizumi's golden age that lasted a mere three generations until 1189, when the city was razed by Minamoto Yoritomo, soon to become Japan's first shogun who was in pursuit of his brother and rival Yoshitsune, who was being given protection by the Fujiwara leader. After the fall of the Fujiwaras the town sank back into obscurity, with most of the buildings destroyed. When Matsuo Bashō visited the area in 1689 he reflected on the impermanence of human glory:
Ah, summer grasses!
All that remains
Of the warriors dreams