Tracing the Origins of the Japanese Sword: Blade Culture and Continental Metalwork in the Jomon and Yayoi Periods

From Stone and Bone to Metal—The Dawn of Sword Culture in the Archipelago

When we in the modern era hear "Japanese sword," we envision a beautifully curved blade, forged from finely-worked tamahagane into a gracefully arcing weapon. Yet this refined form is merely a flower blooming at the end of a long history. If we trace its roots, we arrive at the soil of prehistoric times—the Jomon and Yayoi eras.

The people of the Jomon period (approximately 14,000 years ago to around the 3rd century BCE) used stone arrowheads and stone knives—made by chipping obsidian or shale—as weapons and hunting tools. In particular, obsidian from Hokkaido and the Nagano Wada Pass was transported as far as Kyushu via trade routes, demonstrating that the island society of that time was never an isolated, closed space. However, the technology of metal tools—that is, bronze and iron—was not developed independently by the Jomon people. It was foreign knowledge transmitted from the continent across the sea.

The Shock from the Continent—The Arrival of Bronze and Iron Swords

The opening of the Yayoi period was marked by the arrival of revolutionary metal tool technology via the Korean Peninsula, alongside the introduction of wet-rice agriculture. Recent radiocarbon dating suggests that the beginning of the Yayoi period may date back to around the 10th century BCE (according to the National Museum of Japanese History's revised chronology), but it is believed that metal tools became widely prevalent from around the 4th to 3rd century BCE.

The first weapons to appear in the archipelago were made of bronze. From Yayoi-period archaeological sites in northern Kyushu, "narrow-form bronze swords" (saikei doken) have been excavated, which are common to the Mumun pottery culture sphere in southern Korea. These double-edged swords, approximately 30 to 40 centimeters in total length, derive their form from Chinese Liaoning-style bronze swords. While there is evidence they were used as practical slashing weapons, what is noteworthy is that many specimens have been discovered with their blades worn down, or in an unused state.

The arrival of iron swords was somewhat later, with their spread beginning from northern Kyushu from the middle Yayoi period (around the 1st to 2nd century BCE) onward. Iron yielded harder and sharper blades than bronze, so its practicality as a combat weapon was vastly superior. Yet iron tools, too, carried meaning beyond that of mere implements.

Were Bronze Swords and Spears "Weapons"?—Their Transformation into Ritual Objects

In discussing the Yayoi period, three types of bronze ritual implements—bronze swords (doken), bronze spears (dohokou), and bronze bells (dotaku)—are indispensable. Among them, the most dramatic archaeological discovery is the Kojindani Site, excavated in 1984 in Nita County, Shimane Prefecture (now Unnan City). The following bronze vessels were excavated from the slope of a small hill, arranged in an orderly manner.

• Bronze swords: 358 pieces (an astounding number, constituting roughly half of all Yayoi-period bronze swords discovered nationwide)
• Bronze spears: 16 pieces
• Bronze bells: 6 pieces

None of these Kojindani bronze vessels show signs of having been used in actual combat; they were intentionally buried in the ground. Many of the bronze swords lack not only a hamon but even a blade itself, representing so-called "ritual object types." The Yayoi people redefined the bronze swords that had originally come as weapons as "offerings to the gods" or "sacred things imbued with divine spirit."

A similar transformation is seen with bronze spears. In northern Kyushu, they evolved from the practical "narrow-form bronze spear" to the "broad-form bronze spear" (koukei dohokou), becoming so enlarged as to be actually unusable. Some exceed one meter in total length, clearly transcending any function as weapons. It is believed these were symbols of authority and ritual implements meant to visualize a chieftain's "power."

What Kojindani and Kamo-Iwakura Tell Us—The Spiritual World of "Burial"

At the Kamo-Iwakura Site, located approximately 3.4 kilometers in a straight line from the Kojindani Site, 39 bronze bells were excavated as a single cache in 1996. This also represents the largest number of bronze bells discovered nationwide. Why so many bronze vessels were concentrated and buried in the Izumo region (present-day Shimane Prefecture) remains without a definitive explanation.

The very act of "burial" reflects the Yayoi people's religious worldview. Returning bronze vessels to the earth is thought to have been a ritual to seal their spiritual power in the land or to offer it to the deities of the underworld. In an agricultural society, the cycles of fertility and death and rebirth are closely intertwined, and burying blades—tools that originally take life—in the earth may have been paradoxically viewed as pouring vital force back into the land.

The concept of the "connection between blades and spiritual power" took deep root in later Japanese culture. The tachi in Heian-period rituals, the dedication swords offered at shrines, and the Kusanagi Sword (kusanagi no tsurugi), one of the three imperial regalia—all of these lie on the extension of the concept "blades are sacred things," nurtured in the Yayoi period.

The Arrival of the Iron Age and the Deepening of Metal-Working Technology

From the late Yayoi period into the early Kofun period (3rd to 4th century), iron tools rapidly surpassed bronze implements. Iron became the leading material in agricultural implements, tools, and weapons alike, and blacksmithing (kaji) technology developed throughout the archipelago. Early iron swords were straight swords (chokutou), their shape strongly influenced by continental forms. Comparing two representative excavated examples from this period yields the following:

The "straight swords" of this period were not yet Japanese swords. However, the spiritual culture of regarding swords as something more than "mere tools"—possessing names, imbued with spiritual power, and symbolizing hierarchical relationships—was already firmly established.

The Path to the Birth of the Japanese Sword—What Was Inherited from Prehistoric Times

The distinctive curved blade with "sori" (curvature) characteristic of the Japanese sword emerged in the mid-Heian period (9th to 10th century). Born as a curved sword suited to mounted warfare, it later blossomed into a refined blade culture unparalleled in the world through further technical refinement.

However, the spiritual foundation of the profession of sword-making—the ritualistic manufacturing process of praying to the gods, purifying body and mind, and forging steel in a sacred forge—has roots running far deeper. A long spiritual lineage extending from the Yayoi people's offering of bronze swords to the earth and their reverence and awe before their spiritual power flows through the depths of the cultural treasure that is the Japanese sword.

The ancestors of the Jomon and Yayoi periods never thought, "Let us create the Japanese sword." They merely encountered the unknown power of metal, regarded it as sacred, and incorporated it into their social order and cosmology. Through the accumulation of these endeavors, over thousands of years, they ultimately bore fruit in what the world calls the most beautiful blade—the Japanese sword. Even in the modern world of 2026, one can feel the continuity of this long history viscerally by visiting museums and archaeological sites.