Yoshimi Hundred Caves

Nestled in the town of Yoshimi, Saitama Prefecture, the Yoshimi Hundred Caves, or Yoshimi Hyakuana, stand as a remarkable testament to Japan’s ancient history. Despite their name, this National Historic Site, designated in 1923, comprises 219 man-made tombs carved into a tuffaceous sandstone hillside, not merely a hundred. These corridor-type kofun tombs, dating to the late Kofun period (6th to 7th century AD), offer a window into the burial practices and societal structures of early Japan.

The caves were first excavated in 1887 by Tsuboi Shōgorō, a pioneering Japanese archaeologist from Tokyo Imperial University. His discoveries included Jōmon pottery fragments, magatama beads, gold and silver rings, swords, and bronze mirrors, initially leading him to hypothesize that the caves were dwellings for a diminutive race, possibly the Koro-pok-guru of Ainu folklore. However, further research in the 1920s by archaeologists like Mitsutarō Shirai debunked this theory, confirming the caves as burial chambers for high-ranking noble chieftains and their kin. The artifacts and tomb structures align with other late Kofun period sites, such as those at the nearby Kaziwazaki Plateau, reinforcing their funerary purpose.

Each tomb features a one-meter-square entrance leading to a larger inner chamber, typically two to three meters square, with some extending deeper. Many contain elevated platforms, likely for coffins or bodies, and some have multiple pedestals, indicating use for several burials. Originally sealed with schist slabs, these tombs were reserved for local elites during a time when the Yamato polity, the precursor to Japan’s imperial court, was still consolidating power. The caves’ construction in soft tuffaceous sandstone, similar to materials used in Oita Prefecture’s stone Buddhas, made them relatively easy to carve with primitive tools.

Beyond their ancient origins, the site has a layered history. During World War II, the Nakajima Aircraft Company repurposed part of the site, destroying about one-tenth of the caves to build an underground aircraft engine factory using forced Korean labor. These tunnels, though now closed, add a somber modern chapter to the site’s story. Additionally, the presence of rare luminous moss (Schistostega pennata), designated a Natural Monument in 1928, enhances the site’s allure. Today, the Yoshimi Hundred Caves remain a captivating destination, blending ancient burial traditions with natural and historical significance.

The Koro-pok-guru of Ainu Folklore:

In the vibrant lore of the Ainu, Japan’s indigenous people, the Koro-pok-guru are depicted as a diminutive race, barely a foot tall, who lived in harmony with the land. These shy, benevolent beings, whose name translates to “people under the butterbur leaves,” were said to dwell in underground pits or caves, their homes concealed beneath foliage. Ainu tales describe them as skilled artisans, crafting intricate pottery and stone tools, and engaging in trade with humans under the cover of night, vanishing if seen. Legends suggest they were the original inhabitants of Japan, predating even the Ainu, their small stature offering protection from predators and harsh climates. The Yoshimi Hundred Caves, with their one-meter-square entrances and spacious interiors carved from soft tuffaceous sandstone, align strikingly with these stories, suggesting they could have been homes for such a people.

Archaeological Evidence and Shōgorō Tsuboi’s Hypothesis:

In 1887, Shōgorō Tsuboi, a pioneering Japanese anthropologist, excavated the Yoshimi Hundred Caves in Saitama, unearthing artifacts that breathed life into Ainu folklore. His discoveries included Jōmon-era pottery, magatama beads, and miniature tools—items small enough to suit a diminutive race. Tsuboi hypothesized that the caves, originally dwellings, were later repurposed as Kofun-period tombs by the Yamato people. The small entrances, ideal for a tiny population, and the presence of sophisticated artifacts supported his belief in the Koro-pok-guru’s existence. Though skeletal remains were inconclusive, their small size hinted at a unique population. Tsuboi’s work proposed that these caves were once vibrant homes, their design reflecting the secretive, nature-bound lifestyle of the Koro-pok-guru described in Ainu tales.

Enduring Mystique and Supporting Theories:

The Koro-pok-guru hypothesis gains strength from the convergence of folklore and archaeology. The Ainu’s oral traditions, rich with details of a hidden people, find a potential echo in the Yoshimi caves’ structure and artifacts. Modern scholars note that folklore often preserves memories of ancient cultures, and the Koro-pok-guru may represent a real, perhaps isolated, group adapted to their environment. The caves’ accessibility and the region’s resources suggest a sustainable lifestyle for a small-statured people. While definitive proof remains elusive, the blend of Ainu legend, Tsuboi’s findings, and the caves’ unique design invites belief in a forgotten race, their legacy etched into Japan’s storied past.