The Emishi were natives of northern Honshu that opposed and resisted the rule of the Japanese Emperors during the late Nara and early Heian periods (7th-10th centuries A.D.). At the end of the Heian period (12th C.), those Emishi who were still outside the authority of the state became known as Ezo.
According to earlier Japanese tradition (and Ainu oral history) the Emishi are said to be ancestors of, or related to, the Ainu. There are arguments and evidence for and against this theory.
The Emishi were represented by different tribes. The Emishi in northeastern Honshu were semi-nomadic and relied on their horses in warfare. Their livelihood was based on hunting and gathering as well as the cultivation of grains such as millet, barley, wheat and beans. They developed a unique style of warfare that relied on horse archery and hit and run tactics that proved very effective against the slower contemporary Japanese imperial army that relied on mostly heavily armed foot soldiers.
The first major attempts to subjugate the Emishi by the emperors of Japan, particularly Emperor Kammu in the late 8th century were largely unsuccessful. The imperial armies modelled after the mainland Chinese were no match for the guerilla tactics of the Emishi.
During the 9th century the emperors began to rely on the powerful regional clans - introducing the title of Shogun and relying on hereditary warriors who became the Samurai. Ironically, it was the development of horse archery and the adoption of Emishi tactics by the early Japanese warrior class that led to the Emishi defeat. They either submitted themselves to imperial authority or migrated further north, some to Hokkaido. By the mid-9th century most of their land in Honshu was conquered and they ceased to be independent. However, they continued to be influential in local politics as powerful Emishi families who submitted themselves to Japanese rule eventually created feudal domains in the north that became semi-autonomous. In the two centuries following the conquest a few of these became regional states that came into conflict with the central government.
Recent scholarship has created a much more complicated portrait of this people. By and large, they are seen as indigenous to Japan and not simply as ancestors to the Ainu, but descendants of the Jomon. Even though historically they emerge as serious challengers to the nascent Japanese state they had inherited a rich and separate tradition that went back several millennia before the Japanese speakers came to the islands of Japan. Furthermore, some related people have now been identified as having been some of the first Americans to have crossed the Bering Sea as remains of one individual known as "Kennewick Man" found in 1996 in Washington State attest.
In the study of Jomon skeletal remains dating from thousands of years ago, a direct connection with the modern Ainu was confirmed, showing a definite linkage between the two groups. This linkage however, shows that the Jomon people were very different from modern Japanese and other modern East Asians. The physical appearance of a number of the Ainu who were first encountered by the Europeans in the 19th Century were similar to Caucasians, and thus caused quite a stir among contemporary academics, and has spurred debate about their origins. It is thus surmised that the Jomon also were physically unlike that of other East Asians. This said, physical anthropologists have found that diachronically, and geographically, the skeletal structure of the Jomon population changed over time from southwest to northeast, paralleling the actual migration of Japanese speakers historically, so that more Jomon traits are preserved in the north.
Soon after the Second World War, mummies were discovered in Hiraizumi (the capital city of the Northern Fujiwara), which were thought to be of people related to the Emishi who had originally submitted to Yamato rule, and hence were thought to have been related to the Ainu. However, after further research on the mummies it was found that the rulers of Hiraizumi were like other Japanese of the time, and certainly not related to ethnic Ainu. This was seen as evidence that the Emishi were not related to the Ainu. This had the effect of popularizing the idea that the Emishi were like other contemporary ethnic Japanese who lived in northeast Japan, outside of Yamato rule.
However, the so-called Emishi rulers of Hiraizumi were not actually direct descendants of that ethnic group. It was customary for local rulers to take on local titles that would suggest a direct ancestry. There is some doubt that the Northern Fujiwara had some Emishi blood in them, and for the most part they were part of the Japanese aristocracy.
If the Northern Fujiwara (not related to the Fujiwara of Kyoto) were related to Kyoto aristocracts the whole idea of intermarriage with local Emishi may not have been possible. On the other hand, the Abe, thought to be an Emishi family, had some connection to the Northern Fujiwara, if so they may have been a quarter Emishi. This just shows that among historians the bloodline of the Northern Fujiwara is not at all clear.
It is not known how much the Emishi population changed as Japanese settlers and frontiersmen began to live in their territories even before the conquest. The Japanese established trading relations with them where horses were imported and iron tools and weapons exported. To complicate matters, some ethnic Japanese allied themselves with the Emishi in their wars against the Yamato court. The latter were known in the Nihongi as "Japanese captives" of the Emishi.
The strongest argument for the theory that the Emishi were ancestors of the Ainu comes from historical documents. One of the best sources of information comes from outside Japan, from contemporary Tang Dynasty and Song Dynasty histories as these describe dealings with Japan. For example, there is a record of the arrival of the Japanese foreign minister in AD 659 where conversation is recorded with the Tang Emperor. In this conversation we have perhaps the most accurate picture of the Emishi recorded for that time period.
Two Emishi, a man and woman, from contemporary Tohoku (northeastern Japan) known as "Michi-no-oku" by the Japanese accompanied the minister Sakaibe no Muraji to Tang China. The emperor was delighted with the two Emishi because of their "strange" physical appearance. This was an emperor who was most likely the illustrious Emperor Tang Taizong who was familiar with many ethnic groups throughout his Empire, from Uighurs and Turks to Middle Eastern traders. However, he probably did not have any contact with Europeans. The Japanese envoy for his part describes the contemporary relationship with the Emishi as allies (gentle Emishi), enemies (rough Emishi), and distant Tsugaru Emishi (located in present-day northern Aomori, southern Hokkaido). All Chinese documents refer to them as having a separate state north of Japan and calls them "mojin", literally 'hairy people'. This is also corroborated by Japanese sources such as the Nihongi, described consistently as having long beards and as "hairy", characteristics that have been used to describe the Ainu into the modern period.