In ancient times, the Japanese noted the presence of a "Hinomoto" (people of the east) were established on the Pacific coast of Hokkaido. It can be believed this group were the ancestors of the Sumunkur Ainu.[3]
In the 1600s, the Sumunkur Ainu gradually came into conflict with the Menasunkur Ainu. In 1653, the Sumunkur chief Onibishi killed the Menasunkur chief Camoktain. Shakushain, who succeeded Camoktain as head chief, retaliated by waging war on the Sumunkur and killing Onibishi. Shakushain then went on to declare war on the Matsumae Domain, stationed on the very south of Hokkaido, in Shakushain's Revolts, before being defeated and killed.
After Shakushain's Revolt, the control of the Ainu people by the Matsumae domain strengthened considerably. In modern Hokkaido, the population density of the Ainu people is high in the Iburi and Hidaka regions, and there is a theory that this may be because the Sumunkur were more friendly to the Matsumae domain than the Menasunkur Ainu and Ishikari Ainu (another subgroup located to the north of the Sumunkur Ainu).[4]