Hamajiriya Shell Mound

Hamashiriya Shell Mound: A Medieval Abalone Trading Post on Japan's Remote Shimokita Peninsula

On the rugged northeastern coast of the Shimokita Peninsula in Aomori Prefecture, where the Pacific Ocean meets the Tsugaru Strait, lies one of Japan's most unusual archaeological sites. The Hamashiriya Shell Mound (浜尻屋貝塚) is a nationally designated historic site that tells the remarkable story of a medieval fishing village that thrived as a center for dried abalone production — a luxury commodity that once traveled from this remote corner of northern Honshu all the way to the tables of China's elite.

Unlike the vast majority of Japan's shell middens, which date from the prehistoric Jōmon period, the Hamashiriya Shell Mound is exceptional for belonging to the Muromachi period (14th–15th century). This rare medieval site offers an extraordinary window into the international trade networks that connected even the most far-flung communities of medieval Japan with the broader world of East Asian commerce.

What Is the Hamashiriya Shell Mound?

The Hamashiriya Shell Mound is an archaeological site located in the village of Higashidōri on the Shimokita Peninsula of Aomori Prefecture, in the far north of Japan's main island of Honshu. It consists of a series of 14 shell middens along with the remains of an adjacent settlement, dating from the early 14th to the mid-15th centuries — approximately 600 years ago.

What makes this site truly distinctive is its composition. While most Japanese shell middens contain a variety of shellfish species, the Hamashiriya middens consist almost exclusively of abalone shells, each averaging about six centimeters in diameter. This massive accumulation of abalone shells points to an operation far larger than simple household consumption. Alongside the shell deposits, archaeologists have discovered the remains of ovens, foundation holes for several buildings, and wells — evidence of a well-organized settlement dedicated to the processing of abalone.

The site is believed to mark the location of the original Shiriya village, which later relocated to its present position near Cape Shiriyazaki. The entire fishing village lies buried beneath thick layers of abalone shell deposits, preserving a remarkably complete picture of medieval coastal life in northern Japan.

Why Was It Designated a National Historic Site?

The Hamashiriya Shell Mound was designated a National Historic Site (国指定史跡) by the Japanese government in 2006. This designation recognized several factors of outstanding cultural and historical significance.

First, the site is exceptionally rare as a medieval shell mound. Japan is home to more than 2,000 known shell middens, but the vast majority date from the Jōmon period (roughly 14,000–300 BCE). A shell mound from the Muromachi period is an extraordinary find that fills a significant gap in our understanding of medieval coastal communities.

Second, the archaeological evidence strongly suggests that this site functioned as a specialized factory for the production of dried abalone. During the Muromachi period, trade between Japan and China flourished under the tally trade system (勘合貿易) established by Shogun Ashikaga Yoshimitsu. Dried abalone was a highly prized export commodity, frequently mentioned in contemporary trade documents. The Hamashiriya site provides tangible physical evidence of this industry at its point of origin.

Third, the variety of artifacts discovered at the site — including both Japanese and Chinese coins, fragments of Japanese and Chinese ceramics, and northern-style bone and antler tools — demonstrates the wide-ranging trade connections that linked this remote peninsula to broader East Asian commercial networks. These findings reveal that even communities at the very edge of the Japanese archipelago participated actively in international trade during the medieval period.

Additionally, a fragment of a human skull discovered during excavations in 2002 was analyzed and determined to date from approximately 500 to 700 years ago. The cranial features showed traits shared by both the Ainu people and contemporary Japanese, providing important evidence about the ethnic composition of medieval northern Honshu communities.

The Dried Abalone Trade: Connecting Northern Japan to China

To fully appreciate the significance of the Hamashiriya Shell Mound, it helps to understand the importance of dried abalone in East Asian trade. Abalone has been revered in Japan since ancient times — the practice of making "noshi-awabi" (dried, stretched abalone) is the origin of the decorative "noshi" paper still attached to formal gifts in Japan today.

In Chinese cuisine, dried abalone has long been considered one of the most prestigious luxury ingredients, essential for grand banquets and celebrations. The Chinese saying "without abalone, the banquet is incomplete" reflects just how central this ingredient was — and remains — in Chinese culinary culture.

During the Muromachi period, Japanese dried abalone was exported to China through the tally trade system, which operated from the late 14th century. This trade later continued and expanded during the Edo period, when dried abalone, sea cucumber, and shark fin became known as the "Three Bale Goods" (俵物三品) — Japan's most important marine exports to China.

The cold, nutrient-rich waters around the Shimokita Peninsula provided ideal conditions for harvesting Ezo abalone, which grows slowly over seven to eight years in these northern seas, developing an exceptionally dense and flavorful meat. The Hamashiriya Shell Mound suggests that this region was already involved in large-scale abalone processing centuries before the Edo period trade reached its peak.

Highlights and What to See

The Hamashiriya Shell Mound is an open archaeological site without dedicated public facilities, which gives visitors a uniquely authentic and contemplative experience. Here, there are no glass display cases or reconstruction models — just the raw landscape of history itself.

Surrounding Attractions

A visit to the Hamashiriya Shell Mound can be combined with exploration of the many natural and cultural treasures of Higashidōri Village and the wider Shimokita Peninsula.