In some historical documents it can be confirmed that a group called "Ezo," who seem to have been identical to today's Ainu, already lived in Japan by the thirteenth century through the fourteenth century.
13世紀から14世紀頃には、現在アイヌと呼ばれる民族と同一とみられる「蝦夷」が存在していたことが文献史料上から確認される。