熊祭りは，20世紀にはヨーロッパからアジア，アメリカの極北から亜極北の森林地帯の狩猟民族の間に分布していた。それは，「森の主」，「森の王」としての熊を歓待して殺し，その霊を神の国に送り返すことによって，自然の恵みが豊かにもたらされるというモチーフをもち，広く分布しているにもかかわらず，その形式は著しい類似を示す。そこで人類学の研究者は，熊祭りは世界のどこかで一元的に発生し，そこから世界各地に伝播したという仮説を提出している。しかし，熊祭りの起源については，それぞれの地域の熊儀礼の痕跡を歴史的にたどることによって，はじめて追究可能となる。熊儀礼の考古学的証拠は，熊をかたどった製品と，特別扱いした熊の骨である。熊を，石，粘土，骨でかたどった製品は，新石器時代から存在する。現在知られている資料は，シベリア西部のオビ川・イェニセイ川中流域，沿海州のアムール川下流域，日本の北海道・東北地方の３地域に集中している。それぞれの地域の造形品の年代は，西シベリアでは４，５千年前，沿海州でも４，５千年前，北日本では７，８千年前までさかのぼる。その形状は，３地域間では類似よりも差異が目につく。熊に対する信仰・儀礼が多元的に始まったことを示唆しているのであろう。その一方，北海道のオホーツク海沿岸部で展開したオホーツク文化（４～９世紀）には，住居の奥に熊を主に，鹿，狸，アザラシ，オットセイなどの頭骨を積み上げて呪物とする習俗があった。それらの動物のうち熊については，仔熊を飼育し，熊儀礼をしたあと，その骨を保存したことがわかっている。これは，中国の遼寧，黄河中流域で始まり，北はアムール川流域からサハリン，南は東南アジア，オセアニアまで広まった豚を飼い，その頭骨や下顎骨を住居の内外に保存する習俗が，北海道のオホーツク文化において熊などの頭骨におきかわったものである。豚の頭骨や下顎骨を保存するのは，中国の古文献によると，生者を死霊から護るためである。オホーツク文化ではまた，サメの骨や鹿の角を用いて熊の小像を作っている。熊の飼育，熊の骨の保存，熊の小像は，後世のアイヌ族の熊送り（イヨマンテ）の構成要素と共通する。熊の造形品は，オホーツク文化に先行する北海道の続縄文文化（前２～７世紀）で盛んに作っていた。続縄文文化につづく擦文文化（７～11世紀）の担い手がアイヌ族の直系祖先である。彼らは，飼った熊を送るというオホーツク文化の特徴ある熊祭りの形式を採り入れ，自らの発展により，サハリンそしてアムール川下流域まで普及させたことになろう。それに対して，西シベリアでは，狩った熊を送るという熊祭りの形式を発展させていた。そして，長期にわたる諸民族間の交流の間に，熊祭りはその分布範囲を広げる一方，そのモチーフは類似度を次第に増すにいたったのであろう。

The bear festival had spread among the hunting peoples in the forest zones of the extreme north and sub-extreme north in Europe, Asia and North America by the 20th century. The motif of the festival is that the beauty of nature would be recompensed by killing bears, which were “the masters of the forest” or “the kings of the forest”, and, after they had feasted their spirits, they would go back to the world of the Gods. Although it spread over a wide area, the styles of the festivals in different places show a surprising resemblance. Ethnologists have hypothesized that the bear festival might have originated in one place in the world and then spread widely from there. However, the origin of the bear festival can be traced only by evaluating the evidences of ritualistic treatment of bears in each district.The archaeological evidence for the ritualistic treatment of bears consist of artifacts shaped like bear and bear bones given special treatment. The artifacts shaped like bears made of stones and clay along with bones occur in the Neolithic period. The well-known historical remaining objects were excavated mainly in three places; the central basins of the Ob, the Jenisei rivers in Western Siberia; the lower basin of the Amur river in the Maritime Province of Siberia; as well as the Hokkaidō and Tōhoku districts in Japan. The production dates of these products in each area, in Western Siberia and the Maritime Province of Siberia, can be traced to 4000 or 5000 years ago, and in Northern Japan, amazingly, to 7000 to 8000 years ago. The differences in the form or shapes of the products in these three areas are more recognizable than the resemblances. This suggests that the worship and rituals of the bears may have started in many places.The Okhotsuk culture (the 4th-9th century), developed along the coast of the sea of Okhotsuk in Hokkaidō. It was their custom to pile skulls, mainly of bears but also of deer, raccoon dogs, seals and fur seals, at the back of the house, as fetishes. For the bears among these animals, we know for certain that they fostered baby bears, killed them after ritualistic treatment and preserved their bones. This is determined from their custom of keeping pigs, preserving their skulls and mandibles in and out of their houses. This started in the Liaoning district and the middle basin of the Huang river in China and spread to the basin of the Amur river and Sakhalin as the northern limit and to Middle East Asia and to Oceania as the southern limit. This custom was changed in the Okhotsuk culture, there they used the skulls of bears instead of pigs. According to the old historical materials from China, the purpose of preserving the skulls and the mandibles of pigs was to protect the people from evil spirits.In Okhotsuk culture, they also produced small statues shaped like bears made of shark bones and horns of deer. Fostering bears, preserving the bones of bears and producing the small statues of bears are common features of the “Iyomante” event (sending-off the bears) known as “Iyomante” by the Ainu people. In the Epi-Jōmon culture (the 2nd century B.C. to the 7th century A.D.) proceeding the Okhotsuk culture in Hokkaidō, bear-shaped artifacts were plentiful. The direct ancestor of the Ainu ethnic group precede Satsumon culture (the 7th to 11th century) which follows the EpiJōmon culture. They introduced the style characteristic of the “Iyomante”. They send off the bears to the world of Gods after they killed the bears. This custom spread to Sakhalin and the lower basin of the Amur river during the expansion of their occupation in that area.In Western Siberia, a different style of the bear festival developed. They killed the bears after they had hunted them. During the cultural exchange between various people over a long period, there was a gradual increase of resemblance between practices, during which the bear festival spread widely.

source:https://www.rekihaku.ac.jp/outline/publication/ronbun/ronbun3/index.html#no60