Rikkoku Gohon: The Historical Hierarchy of Sword-Producing Regions and Material Quality Established in Late Heian Japan

What is Rokukoku Gohon — The Primordial Standards for Japanese Sword Quality Evaluation

"Rokukoku Gohon" (六国五本) is a hierarchical system of quality evaluation regarding the production region, materials, and forging techniques of Japanese swords, said to have formed during the late Heian through early Kamakura periods. While this concept occupies an important position in sword appraisal culture, there are various theories about its establishment period and content, and it remains a subject of ongoing debate in modern sword research.

"Rokukoku" refers to six provinces (ritsuryo kingdoms) that were particularly distinguished as production regions for swords. Generally, the six provinces of Yamashiro, Yamato, Bizen, Sagami, Mino, and Echizen are most commonly cited. However, depending on the source, some texts substitute Satsuma for Sagami, and the enumeration of provinces is not necessarily fixed. "Gohon" is said to represent a hierarchy of materials used in sword production, but due to sparse documentation in ancient texts, it is often transmitted through later appraisal documents and oral tradition.

The Breakdown of the Six Provinces — Why These Six Production Regions Were Selected

Each production region selected as part of the six provinces had geographical and technical backgrounds that fostered superior sword culture.

Yamashiro Province (Kyoto) was the center of court culture centered on Heian-kyo and developed as a supply region for swords for the nobility, warrior class, and temples. It produced famous schools such as the Awataaguchi, Sanjo, and Kite schools, and was characterized by refined and elegant craftsmanship.

Yamato Province (Nara) was a center of sword production from ancient times and was home to sword-making groups connected with many large shrines and temples. The five Yamato schools of Tegaki, Senjuin, Taima, Hojo, and Shirigake are famous, and they produced many simple yet practical swords.

Bizen Province (present-day eastern Okayama Prefecture) is known as Japan's largest sword production region. The abundant natural environment of the Yoshii River basin—with its iron sand, charcoal, and water—was ideal for sword forging, and a major industry centered on Osafune was established. The choji-midare hamon characteristic of the Bizen tradition is highly valued worldwide.

Sagami Province (Kanagawa) was positioned at the center of the warrior regime as the seat of the Kamakura shogunate, and was home to Yukimitsu, Masamune, Sadamune, and others considered founders of the Soshu tradition. The Soshu tradition is characterized by dramatic itame jihada and strong nie in the hamon, exerting enormous influence on sword making in later periods.

Mino Province (Gifu) was a region that rose to prominence during the Muromachi period and supplied practical swords suited for mass production centered on Seki. It was characterized by forging methods that emphasized folding and tempering, with bright and keen hamon, and was widely favored by Sengoku warlords.

Echizen Province (Fukui) was a relatively newer production region among the six provinces, but outstanding swordsmiths such as Echizen Yasutsugi gained prominence and established a high position as official shogunate swordsmiths.

The Concept of Gohon — The Hierarchy of Material Quality

The concept of "Gohon" is more ambiguous compared to "Rokukoku" and is difficult to define conclusively. It is likely a hierarchical classification of tamahagane quality viewed from the perspectives of production region, manufacturing method, and carbon content. It is said that iron sand producing regions known for producing high-quality tamahagane (such as regions using tetsu-ana-nagashi in the Chugoku Mountains) were positioned at the top, with lower-quality iron placed below. The specific content of gohon varies by source, with various classifications existing such as tamahagane, pig iron, blade iron, and nanban iron.

Formation Context in the Heian and Kamakura Periods

The late Heian through Kamakura period, when the concept of Rokukoku Gohon was formed, was an era marked by the rise of the warrior class and a sharp increase in sword demand. With the emergence of warrior groups, differences in sword quality became directly connected to a warrior's survival, and the formation of an evaluation framework asking "which production region produces superior swords" was a natural development.

During the Insei period's sword appraisal, a hierarchical consciousness emerged regarding which provinces' swordsmiths were recognized as "master craftsmen," and this is thought to have developed into regional evaluation. As authoritative consumers such as the imperial court, warrior clans, and major temples identified and evaluated quality differences by production region, this system gained authority.

Impact on Appraisal Culture — The Legacy of Rokukoku Gohon

The concept of Rokukoku Gohon became deeply rooted in sword appraisal culture from the Edo period onward. Sword appraisers, beginning with the Honami family, referred to Rokukoku Gohon knowledge when estimating a sword's production region and developed methods to narrow down the region based on characteristics of the sword's shape, jihada, and hamon.

This conceptual framework was developmentally inherited into the Five Traditions concept in modern sword research—the five major schools of Yamashiro, Yamato, Bizen, Soshu, and Mino. The Five Traditions can be seen as a reorganization of Rokukoku excluding Echizen, with emphasis placed on the Soshu tradition as a synthesis of the various schools.

In modern sword appraisal as well, regional estimation begins by determining "which tradition does it belong to." The technique of estimating a sword's production region from complex characteristics—the jihada pattern, the patterns of the hamon, and the finishing of the nakago—is nothing but the result of the continued refinement of the quality evaluation tradition that began in the Heian and Kamakura periods. Rather than being merely a historical classification system, Rokukoku Gohon, in providing an epistemological framework for how to interpret the aesthetic value of Japanese swords, can be said to be a foundational concept of sword culture.