Buyeo Cavalry and the Seven-Branched Sword: Rethinking the Deep Roots of the Early Japanese State

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1. A Western Japanologist Who Ended Up in Korea

John Carter Covell (1910–1996) is a fascinating, if now semi-forgotten, figure in East Asian studies.

• He was one of the first Westerners to earn a doctorate in Japanese art history,

• Taught East Asian art at universities in the United States,

• And later became best known for books such as Korean Impact on Japanese Culture: Japan’s Hidden History, in which he argued that much of what we call “traditional Japanese” culture has deep roots on the Korean peninsula. 코리아타임스

From the late 1970s he relocated to Korea, spent roughly eight years based there, and published hundreds of essays in English on Korean art, archaeology, Buddhism, and early Korea–Japan relations. 코리아타임스

The more deeply he studied Japanese art, the more convinced he became that many motifs, techniques, and even religious forms visible in early Japanese material culture could not be fully explained without looking to Buyeo, Goguryeo, Baekje, Gaya, and Silla on the Korean side. It is from this perspective that he developed his most daring ideas about “Buyeo cavalry and the Wa (倭).”

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2. The Seven-Branched Sword at Isonokami: A Korean Gift in a Japanese Shrine

At the heart of Covell’s narrative stands a single, extraordinary object: the Seven-Branched Sword (Shichishitō, 七支刀).

This ceremonial iron sword is preserved at Isonokami Shrine (Isonokami Jingū) in Nara Prefecture, one of Japan’s oldest weapon shrines. Its blade has a central spine from which six subsidiary blades branch out—three on each side—giving it a stylized, tree-like profile.

Most scholars date the sword to the late 4th century CE and agree that it was never intended for combat. Instead, it was a prestige object, a diplomatic or ritual gift. Crucially, it carries a partially corroded Chinese-character inscription. While several characters are now lost, the core of the text has been reasonably reconstructed as something very close to:

“On the day of the sixth month of the X year,
made of hundred-times refined steel,
this sword is presented by the King of Baekje
to the King of Wa…”

Although individual readings differ—especially regarding the exact era year and the precise phrasing—there is broad consensus on two points:

1. The sword was produced in Baekje, a powerful kingdom in southwestern Korea.

2. It was presented to the ruler of Wa (the Yamato polity) as a formal gift, symbolizing a high-level diplomatic relationship. EBSCO

In other words, at the very moment when a centralizing political entity was emerging in the Japanese archipelago, its rulers were receiving inscribed elite weaponry from a Korean kingdom. That alone is enough to show that early Yamato was not developing in isolation.

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3. The Kofun Period and Korean Connections: What Mainstream Scholarship Accepts

Covell did not start from thin air. By the mid-20th century, archaeologists in Japan and Korea were already uncovering evidence that the Kofun period (ca. 3rd–6th c. CE) was closely entangled with the Korean peninsula. Encyclopedia Britannica

Key points widely recognized today include:

• Burial mounds and grave goods
  Enormous keyhole-shaped tombs (zenpō-kōen-fun) in the Japanese archipelago, usually interpreted as elite or royal tombs, often yield:

  • Lamellar iron armor and helmets,

  • Elaborate horse trappings,

  • Ring-pommel swords and other weapon types,
    that closely resemble contemporaneous finds from Baekje, Gaya, and Silla. Encyclopedia Britannica+1

• Ceramic and metallurgical technology
  The spread of high-fired Sue ware ceramics and advancements in ironworking appear linked to the arrival of artisans and technologies from the Korean peninsula. Encyclopedia Britannica

• Elites of foreign origin
  Both Japanese chronicles and later genealogies mention immigrant lineages from “Baekje people” (Kudara no kuni no hito), “Gaya people,” and others, some of whom rose to prominent positions in the Yamato court. KJIS

Modern scholarship therefore tends to see early Yamato not as a purely indigenous development, but as a hybrid political community shaped by intense interaction with peninsular polities—through migration, marriage alliances, technology transfer, and military cooperation.

Up to this point, Covell’s emphasis on “Korean impact” is broadly aligned with a growing body of research.

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4. Covell’s Leap: From Interaction to “Buyeo Cavalry Conquest”

Where Covell becomes truly controversial is in how far he pushes this Korean factor.

He draws attention to three interlinked strands:

1. Buyeo and Goguryeo as cavalry states
   Northern polities such as Buyeo and Goguryeo built their power on horse-mounted warfare, iron weapons, and a militarized aristocracy. Chinese chronicles portray them as formidable border powers capable of confronting Chinese commanderies and later dynasties. 코리아타임스

2. The Kofun-era “horse-and-armor package” in Japan
   The sudden appearance, in 4th–5th century Kofun tombs, of:

   • Complete sets of armor and helmets,

   • Horse gear,

   • Weapons matching Korean prototypes,
     suggests to Covell not merely trade, but the relocation of entire cavalry elites into the Japanese archipelago. Encyclopedia Britannica+1

3. The Seven-Branched Sword as Buyeo–Baekje symbolism
   For Covell, a heavily stylized iron ritual sword, made in Baekje and dedicated to the ruler of Wa, fits the profile of a gift exchanged among ruling houses of shared or related origin, perhaps tracing back to Buyeo cavalry traditions.

From this, he sketches a bold scenario:

During the 4th century,
groups of Buyeo–Goguryeo–Baekje–linked cavalry elites crossed the sea,
established dominance in parts of the Japanese archipelago,
and played a leading role in forging the Yamato state.

In his telling, later Japanese narratives—which claim that the legendary Empress Jingū conquered the Korean “Three Han” and brought wealth and culture back to Japan—may actually be inverted memories of these cross-strait power struggles.

What in Japanese myth is framed as “Japan conquering Korea” might, in his reading, be the political memory of Korean or Buyeo-linked elites taking power in Japan, recast generations later in a more flattering direction.

This is an imaginative and stimulating hypothesis—but it goes beyond what the available evidence can definitively prove.

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5. The Empress Jingū Legend: Myth, Memory, and Ideology

The Empress Jingū narrative in the Nihon Shoki (Chronicles of Japan) tells of a semi-divine consort who, guided by the gods, launches a punitive expedition against “Sankan” (the Three Han in Korea) and returns in triumph, establishing Japan’s hegemony over the peninsula.

Modern historians across Japan, Korea, and the broader field of East Asian studies generally agree that:

• The story was compiled several centuries after the alleged events,

• It does not align with contemporary Korean or Chinese records,

• And it functioned primarily as a mythic charter for later claims of supremacy over Korea.

Recent scholarship also emphasizes that the legend was repeatedly re-used in later Japanese history—especially in the modern period—as a symbol of imperial expansion and as a way to imagine Korea as Japan’s “ancient subordinate.”

Covell’s suggestion—that this legend might be an ideological reversal of much more complex early interactions, including migration and perhaps military intervention from the peninsula into Japan—is not, in itself, implausible as a thought experiment. But it remains speculative.

The key point for a serious blog article is to draw a clear line:

• Fact: the Jingū legend is not a literal historical record and was used to support later political agendas.

• Interpretation: how much of it preserves distorted echoes of real cross-strait military ventures is a matter of debate, not consensus.

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6. What We Can Say with Confidence

If the goal is to present a responsible yet engaging picture for a general readership, it helps to separate out three layers.

(1) Broadly accepted by mainstream scholarship

These are points you can state firmly:

• Korean peninsular polities played a major role in early Japanese state formation.
  Archaeology shows strong technological, artistic, and military influences from Baekje, Gaya, and Silla during the Kofun period, including the spread of ironworking, mounted warfare, temple architecture, and writing.

• The Seven-Branched Sword is a Baekje diplomatic gift.
  Its inscription, despite damage, clearly records a sword made by a Baekje king and presented to the ruler of Wa, underlining a high-level relationship between Baekje and the Yamato court in the late 4th century.

• Empress Jingū’s “Korean conquest” is mythic, not literal history.
  Historians treat it as a later ideological construction rather than as a straightforward record of 3rd-century military campaigns.

(2) Plausible but debated

Here we move into hypotheses that many scholars are open to, but still discuss:

• Peninsular elites as co-founders of Yamato.
  There is substantial support for the idea that immigrants from Baekje and Gaya were not only artisans and scribes but also participated in the political and military elites of the emerging Yamato state. Some may have held key positions at court and in regional rule.

• Shared Buyeo–Goguryeo–Baekje ideological and artistic traditions.
  Iconography, funerary practices, and certain ritual objects suggest a web of related cultures stretching from Manchuria through the Korean peninsula and into the Japanese archipelago.

(3) Covell’s distinctive, high-risk interpretation

Finally, there is the layer that is uniquely Covell’s and should be presented to readers as one scholar’s thesis, not as established fact:

• That Buyeo cavalry groups “conquered” Yamato in a literal, military sense;

• That the Japanese imperial house itself descends primarily from these Korean or Buyeo-origin “adventurers”;

• And that the Jingū legend is a direct inversion of an original Korean conquest.

These ideas are intellectually stimulating and certainly fit the “hidden history” framing of his book titles, but they go well beyond what current evidence compels us to accept.