Historic Battles Series: Thirty-Eight Years’ War

The monument for commending Aterui and More at Kiyomizu-dera in Kyoto


The Emishi was an ancient ethnic group of people who survived in Honshū, particularly in the Tōhoku region. The first mention of the Emishi in record dates to 400 CE. The Chinese records referred to them as ‘the hairy people.’

Some Emishi tribes opposed various Japanese Emperors during the Nara and Heian periods (7th–10th centuries CE). The thirty-eight years’ war is the deadly battle between Emishi and the Japanese Emperor army.

Thirty-Eight Years’ War

The thirty-eight years’ war started in 773 CE with the Korehari no Azamaro defection. He was a high-ranking Emishi leader of the Japanese army in Taga Castle.

The Emishi retaliated along a broad front starting with Momonohu Castle, destroying the garrison before destroying several forts along a defensive line from west to east built over the past generation. Even Taga Castle was not left untouched.

Japan’s imperial forces had around 20,000 strong fighters, and they were up against 2000 Emishi warriors.

In 776, Japanese forces sent enormous troops of over 20,000 men to attack the Shiwa Emishi but failed to defeat the enemy, who then successfully counterattacked their foes in the Ōu Mountains. In 780, the Emishi pushed the Sendai plain, burning Japanese villages there. The Japanese were near frenzy as they tried to over-tax and hire more soldiers from the Bandō.

In the 789 CE Battle of Koromo River, the Japanese army under Ki no Kosami Seito shōgun was overwhelmed by the Isawa Emishi under their general Aterui. Four thousand-strong men were attacked as they tried to cross the Kitakami River by a team of a thousand Emishi. The imperial army experienced its most stunning defeat, losing a thousand men, many of whom drowned in the river.

In 794, many important Shiwa Emishi, including Isawa no Kimi Anushiko of what is now Miyagi, became allies of the Japanese. This was a remarkable reversal to the ambitions of those Emishi who still fought against the Japanese. The Shiwa Emishi were a dominant group and successfully attacked smaller Emishi groups as their leaders were elevated into imperial rank. This had the effect of separating one of the most influential and independent Emishi, the Isawa confederation. The newly elected shōgun general, Sakanoue no Tamuramaro, then pushed the Isawa Emishi, relentlessly using soldiers raised in horse archery.

The result was a miscellaneous campaign that ultimately led to Aterui’s final surrender in 802. The battle was officially over, and many Emishi groups submitted themselves to the Japanese royal government. However, skirmishes still occurred, and it was not until 811CE that the Thirty-Eight Years’ War was over.

North of the Kitakami River, the Emishi were still self-governing, but the large scale threat that they posed stopped with the decisive defeat of the Isawa Emishi in 802.


After their battle, some Emishi leaders became part of the administration’s local framework in the Tōhoku, culminating with the Northern Fujiwara management. This government and others such as the Abe and Kiyowara were organized by local Japanese gōzoku and became local semi-independent states based on the Emishi and Japanese people. However, even before these rose, the Emishi people progressively lost their separate ethnicity and culture as they became minorities.

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