Northern and Southern Courts Period and Swordsmith Economics: Wartime Demand Driving Growth and Innovation in Forges

The Nanboku-chō period (1336–1392) is called the "golden age of sword-smiths" in the history of Japanese swords. The sharp increase in weapon demand due to large-scale civil war brought about rapid expansion of the smithing industry and technological innovation. This paper analyzes sword-smith management and economic fluctuations of smithing workshops during this era.

Nanboku-chō Warfare and the Explosion of Sword Demand

The Nanboku-chō upheaval lasted 56 years into the early Muromachi period. During this time, daimyo and military governors throughout the land required vast quantities of swords and blades.

Demand Increase from Warfare

• Rapid Increase in Soldier Numbers: Through mobilization of the shogunal forces led by Ashikaga Takauji, opposing forces of the Southern Court, and regional daimyo across the land, combat participants expanded to hundreds of thousands.
• Rising Attrition Rates: Damage rates in field combat were high, and the lifespan of a single sword became shorter than usual.
• Frequency of Equipment Updates: Bestowal of swords and blades as rewards for military service became more active.

Estimates suggest that tens of thousands to hundreds of thousands of swords were manufactured annually over these 56 years.

Geographic Distribution and Migration of Sword-smiths

In response to increased demand, the migration of sword-smiths became more active.

Expansion of Renowned Sword-Making Regions

• Bizen (Okayama Prefecture): An ancient major production center with hundreds of sword-smiths.
• Soshu (Kanagawa Prefecture): Rose to prominence from the late 13th century to the early 14th century.
• Kyoto: A base for the imperial court and traditional powers.

However, during the Nanboku-chō period, smithing workshops throughout the nation converted to sword manufacturing in response to demand. Smithing craftsmen from Kyushu (Satsuma and Bungo), Etchu (Toyama Prefecture), and furthermore from Owari entered sword manufacture in succession.

Competition for Acquiring Sword-smiths

Daimyo sought to secure prominent sword-smiths.

• Ashikaga Shogunal House: Brought renowned Kyoto sword-smiths into their direct service.
• Ouchi Clan (Daimyo of the Chugoku Region): Recruited sword-smiths from Kyushu and Bizen.
• Shiba Clan (Daimyo of the Tokai Region): Established exclusive supply contracts with excellent Owari sword-smiths.

Individual sword-smiths' self-sale and transfers became common, and conditions for compensation and status assurance rapidly improved.

Organization of Smithing Workshops and Technical Division of Labor

To respond to the explosion in demand, the organization of smithing workshops became more complex.

Changes in Workshop Organization

Previously, workshops were organized on a small scale with 1–3 master sword-smiths and 3–5 apprentices. During the Nanboku-chō period, specialist craftsmen were organized under one master sword-smith.

• Foundation Smithing Craftsmen: Forged the basic shape of the blade (labor-intensive).
• Hardening Craftsmen: Specialists in water-quenching and heat adjustment.
• Polishing Craftsmen: Finishing polishing (sometimes subcontracted to separate craftsperson groups).
• Metal Fittings Craftsmen: Handled attachment of habaki, mekugi, and other fittings.

Through this division of labor, annual production under the same master sword-smith increased to 5–10 times the previous level.

Acceleration of Material Procurement

Supply of tamahagane necessary for sword manufacture also increased rapidly.

Increased Tatara Iron Production

In the Hii River basin of Shimane Prefecture (the ancient principal production site of tatara iron), operations accelerated from 2–3 operations per year to 1–2 operations per month during the Nanboku-chō period.

As a result, tamahagane prices rose gradually, and delivery lead times to sword-smiths were shortened.

Compensation and Status of Sword-smiths

The economic status of sword-smiths improved dramatically.

Changes in Compensation System

Previously (Kamakura period), compensation for one sword was several koku of rice and clothing. During the Nanboku-chō period, it changed as follows.

• Base Compensation: 10–20 koku of rice per sword (5–10 times the previous amount).
• Special Allowances: Bestowal of domain land to renowned sword-smiths (treated as samurai).
• Rewards for Service: Bestowal of fiefs (farmland) in accordance with sword manufacture.

Rise in Social Status

Sword-smiths came to be recognized as elite craftspeople on par with respected master carpenters. Some renowned sword-smiths (such as Bizen's Fukuoka Ichimonji school) participated in political consultation with daimyo as senior retainers, beyond sword manufacture.

Technological Innovation and Diversification of Styles

The increase in demand and compensation simultaneously brought about technological innovation.

Development of New Blade Patterns

The gonomel hamon and midareba established by the Soshu tradition (such as Masamune) in the late Kamakura period became widely disseminated and developed during the Nanboku-chō period. The gonomel hamon features alternating waves in a continuous, powerful appearance, while the midareba is a complex and elegant blade pattern that the Soshu school further developed.

These combined practical utility (durability and cutting performance) with aesthetic value, and were treasured among daimyo and warriors.

Unique Styles by Regional Sword-smiths

Swords with regional characteristics suited to local demand were developed in various areas.

• Satsuma Tradition: Wide and powerful blades adapted to combat styles in southern Kyushu.
• Etchu Tradition: Compact and lightweight, advantageous for mountain warfare.
• Owari Tradition: Prioritizing practicality, budget versions meeting the demand of armed farmers.

End of the Nanboku-chō Period and Transformation of the Sword-smith Industry

When the Nanboku-chō was unified in 1392, warfare ended. Sword and blade demand declined rapidly, and sword-smiths faced a turning point.

Industrial Adjustment

• Many small-scale smithing workshops adapted for warfare closed.
• Renowned sword-smith workshops shifted to producing high-quality swords for collectors.
• Technical division of labor declined, and workshops increasingly returned to individual operation.

However, the sword-manufacturing techniques and organizational knowledge established during this period became the foundation for the subsequent development of sword-smithing.

Summary

The warfare of the Nanboku-chō period brought about a "golden age" of the sword-smith industry. The explosion in demand improved compensation, and the social status of sword-smiths rose sharply. Simultaneously, organization, division of labor, and technological innovation were accelerated. The blade patterns and styles that became widespread and developed during this period are respected today as classics of subsequent sword-blade aesthetics. It is necessary to evaluate historically the technical and economic legacy born from the negative phenomenon of warfare.