This collection of rare materials brings together books, manuscripts, and maps produced during the 18th and 19th centuries that document Japanese exploration and observation of the island and prefecture now known as Hokkaido in Japan, as well as Sakhalin and the Kuril Islands in Russia. For several centuries these areas were inhabited primarily by Ainu peoples, who shared closely related languages, traditions, and modes of existence that were distinct from their ethnic Japanese neighbors to the south. Prior to and during much of the Edo period (1600-1868), the range of Ainu communities also extended south across parts of northern Honshu, the largest of the four major islands that comprise modern Japan, in addition to the eastern Amur River region and southern Kamchatka.

From the viewpoint of ethnic Japanese, or Wajin as the Ainu called them, these northern lands were collectively known as Ezo or Ezochi ("Ezo land"), a name suggestive of less civilized or culturally inferior peoples. Beginning in the 17th century, the Wajin began pushing further into historically Ainu lands, establishing a foothold on the southern part of Hokkaido. In contrast to Ezochi, where the Ainu predominated, territory in this northerly region that was controlled by ethnic Japanese became known as Wajinchi ("Wajin land"). During the 18th and 19th centuries, growing numbers of Wajin set out to explore, survey, and map Ezochi for political, military, and economic reasons.

In the 1870s, the Japanese central government, as part of its mission to modernize and strengthen the country as a bulwark against the Western imperial powers, set out on a colonizing mission of its own—to settle Ezochi with Japanese citizens, reap the benefits of its natural resources, and bring it firmly under Japanese sovereignty. The Ainu, who were primarily hunters and fishers, were displaced from their lands and forced into a settled Japanese agricultural lifestyle. Ainu language and customs were rejected as "uncivilized" and children were forced to attend newly created public schools to hasten their assimilation as imperial Japanese subjects. Today, the number of ethnic Ainu remains difficult to identify precisely, but estimates range from 20,000 up to 200,000.

The materials in the Ainu and Ezochi Rare Collection primarily cover the 18th and 19th centuries. The oldest item in the collection is Ezo shi ("Ezo gazeteer") dating to around 1720, by the noted scholar and high-ranking bureaucrat Arai Hakuseki. This work is the oldest known publication about the Ainu and Ezochi that was based on first-hand accounts, rather than folklore or legends. Because the Ainu did not possess a written language, the materials in this collection include some of the earliest textual accounts of Ainu culture. They also include many color illustrations that document the Ainu people’s unique clothing, housing, cuisine, religion, family structures, and customs, albeit from the perspective of the Wajin rather than the Ainu themselves.