The Ainu or the Aynu (Ainu アィヌ Aynu; Japanese: アイヌ Ainu; Russian: Айны Ajny), in the historical Japanese texts the Ezo (蝦夷), are an indigenous people of Japan (Hokkaido, and formerly northeastern Honshu) and Russia (Sakhalin, the Kuril Islands, and formerly the Kamchatka Peninsula).
The official number of the Ainu is 25,000, but unofficially is estimated at 200,000 due to many Ainu having been completely assimilated into Japanese society and, as a result, having no knowledge of their ancestry.
Recent research suggests that Ainu culture originated from a merger of the Jomon, Okhotsk and Satsumon cultures. In 1264, Ainu invaded the land of Nivkh people controlled by the Yuan Dynasty of Mongolia, resulting in battles between Ainu and the Chinese. Active contact between the Wajin (the ethnically Japanese) and the Ainu of Ezochi (now known as Hokkaido) began in the 13th century. The Ainu formed a society of hunter-gatherers, surviving mainly by hunting and fishing. They followed a religion which was based on natural phenomena.
During the Muromachi period (1336–1573), the disputes between the Japanese and Ainu developed into a war. Takeda Nobuhiro killed the Ainu leader, Koshamain. Many Ainu were subject to Japanese rule which led to a violent Ainu revolt such as Koshamain's Revolt (ja:コシャマインの戦い) in 1456.
During the Edo period (1601–1868) the Ainu, who controlled the northern island which is now named Hokkaido, became increasingly involved in trade with the Japanese who controlled the southern portion of the island. The Tokugawa bakufu (feudal government) granted the Matsumae clan exclusive rights to trade with the Ainu in the northern part of the island. Later, the Matsumae began to lease out trading rights to Japanese merchants, and contact between Japanese and Ainu became more extensive. Throughout this period the Ainu became increasingly dependent on goods imported by the Japanese, and were suffering from epidemic diseases such as smallpox. Although the increased contact created by the trade between the Japanese and the Ainu contributed to increased mutual understanding, it also led to conflict which occasionally intensified into violent Ainu revolts. The most important was Shakushain's Revolt (1669–1672), an Ainu rebellion against Japanese authority. Another large-scale revolt by Ainu against Japanese rule was the Menashi-Kunashir Battle in 1789.
The beginning of the Meiji Restoration in 1868 proved a turning point for Ainu culture. The Japanese government introduced a variety of social, political, and economic reforms in hope of modernizing the country in the Western style. One innovation involved the annexation of Hokkaido. Sjöberg quotes Baba's (1980) account of the Japanese government's reasoning: