僧兵の誕生と武士の台頭The Monk Militarization Era

I typically visit Shinto shrines, but occasionally I also go to Buddhist temples. Among these, I particularly love Kongobu-ji Temple on Mount Koya, established by Kukai, who introduced Esoteric Buddhism to Japan, and Muro-ji Temple in Uda City, Nara Prefecture, known for legends of En no Ozunu, the founder of Shugendo. Sometimes I visit these temples during specific seasons, immersing myself in thoughts about bygone eras. Historically, two key centers in Japanese history are Yamato (modern Nara) and Heiankyo (modern Kyoto). During a certain period of the pandemic, I visited Nara daily to research various topics predating the Heiankyo period, while at other times I based myself in Kyoto to explore the history surrounding Heiankyo itself.

Nara was the heartland where Buddhism quickly rose to prominence after its introduction to Japan, becoming a major political and cultural force. Now, its former power has waned, and the once-glorious Buddhist influence has become a relic of the past, allowing visitors like myself to enjoy quiet contemplation. However, temples such as Kofuku-ji, Todai-ji, and Enryaku-ji on Mount Hiei, though serene today, once had the exact opposite—an intense, often bloody vitality exemplified by the armed monk warriors known in Japan as sohei (僧兵).

Since the relocation of the capital to Heiankyo in 794, in Shitsurae we have briefly traced the rise and fall of the influential Fujiwara clan, who dominated aristocratic politics, and how this contributed to the emergence of the warrior (samurai) class. If the Fujiwara’s decline was one factor in the rise of the samurai, the other crucial factor was undoubtedly the emergence of these militant monks. Particularly from the mid-Heian period onward, Buddhism became deeply entrenched in Japanese society, wielding significant political authority. In major temples, monks began arming themselves and engaging in military activities—a phenomenon unprecedented up to that point.

The backdrop to this development was the decline of the military structure established under the Ritsuryo system dating back to Emperor Tenmu and Empress Jito. This decline led to a military vacuum near the imperial court, coupled with the rapid expansion of powerful temples holding significant religious sway. Behind these changes was Fujiwara no Fuhito (659–720), a behind-the-scenes power broker during Empress Jito’s reign, who laid the groundwork for the Fujiwara clan’s ascendancy. Under the previous Ritsuryo system, provincial governors and local district heads conscripted regional inhabitants as soldiers, but this system had already become dysfunctional by the end of the 9th century. The political turmoil surrounding the imperial succession battles leading up to the establishment of Heiankyo played a significant role in this dysfunction. Emperor Kanmu, who ascended the throne amidst frequent assassinations and rebellions, faced extreme financial difficulties. To preserve the imperial line during these turbulent times, he abandoned Nara, a region plagued by tatari (祟り), spiritual curses, and relocated the capital to the previously insignificant area now known as Kyoto. But the court had no budget of its own, so it had to ask for financial help from the Hata clan, which already governed much of Kyoto and had expanded its influence through a range of industrial technologies.

As a result, Heiankyo was successfully established, but the court’s reliance on powerful clans such as the Hata for financial support led to aristocratic groups originating from these clans gaining significant local power, surpassing even the imperial family. Another noteworthy point in this period of fiscal crisis was the abolition of the official imperial army in 792, creating a vacuum of imperial military power. This vacuum facilitated the rise of local warriors scattered throughout Japan and contributed to increasing banditry and piracy. Meanwhile, major temples like Enryaku-ji and Kofuku-ji received substantial protection and grants of private estates (shoen, 荘園) from the imperial court. This allowed them to build independent economic bases, increasing their influence dramatically—often surpassing that of the court itself. Furthermore, as temple lands and estates expanded significantly, monks began to arm themselves, organizing militarily under the justification of protecting their extensive properties.

Initially, these activities were likely small in scale but became prominent around the 10th century. Although few early records survive, we do have accounts such as the event in 894, when pirates attacked Tsushima, and monks from local temples took up arms and fought. This suggests that initially temples might have had to arm themselves purely for self-defense. However, by 974, one of the major Buddhist power centers, Kofuku-ji Temple in Nara, was engaged in fierce conflict with Enryaku-ji Temple on Mount Hiei over control of the Gion Shrine (now Yasaka Shrine) in Kyoto, with records clearly noting monks armed on both sides. Such incidents were initially sporadic, but eventually, temple leadership began tacitly accepting the presence of armed monks, actively leveraging them to expand their own influence. Thus, the sohei, the militant monks, emerged, signaling a turbulent new era—essentially, the birth of armed groups using religious institutions as cover.

Notably, internal conflicts within the Tendai sect deserve special attention. The Tendai sect was established by Saicho (766–822), who, like Kukai, studied in Tang China, founding its headquarters at Enryaku-ji on Mount Hiei. Although less known today, the critical importance of Enryaku-ji lies in its strategic location. The temple itself was founded in 788, slightly before the establishment of Heiankyo, but it was officially granted the name “Enryaku-ji” by the imperial court only in 851, after Saicho’s death. One crucial reason for situating Enryaku-ji deep in Mount Hiei was its role as a spiritual guardian of Heiankyo, essentially serving as a protector of the imperial family. Central to this arrangement was the concept of kimon (鬼門).

Kimon, which has its roots in China, comes from onmyodo (陰陽道), a practice that flourished in the Heian period, and denotes the ominous northeastern direction believed to be a gateway for oni, evil spirits, and calamities. In 794, viewed from the newly established Heiankyo, Mount Hiei lay directly in this northeastern direction. Thus, by placing Enryaku-ji there, Saicho, deeply connected to the imperial court, intended it as a spiritual fortress protecting the capital. Given the supreme importance attached to this spiritual defense, Enryaku-ji’s expansion was essentially inevitable. Because of its critical role as protector against evil spirits, the temple occupied a special status, essentially off-limits to direct imperial intervention. This was the pivotal factor enabling Enryaku-ji’s growth. Direct imperial interference would symbolically weaken the spiritual defense of kimon, leaving the imperial court with little choice but to tolerate the temple’s increasing autonomy—a strategy that ultimately proved naive.

A significant event symbolizing the “runaway” power of Enryaku-ji occurred in 993, during a split between the Sanmon faction (山門派) of Enryaku-ji and the Jimon faction (寺門派) of Onjo-ji Temple, also known as Miidera. The split began as an internal Tendai sect dispute over authority and legitimacy. Briefly stated, the Sanmon faction claimed orthodox legitimacy and remained at Enryaku-ji on Mount Hiei, while the opposing Jimon faction relocated to Onjo-ji, situated at the southern foot of Mount Hiei, actively pursuing their own agenda. The complexity of this conflict intensified because both Enryaku-ji and Onjo-ji had noble patrons and vast private estates (shoen), employing numerous armed monks for estate management and protection. Additionally, the aristocracy exacerbated the issue, using this religious division as a proxy in their own political struggles within the imperial court, thereby elevating their own status through exploitation of these tensions.

Consequently, this complicated intersection of interests led both the Sanmon and Jimon factions to mobilize their sohei into open warfare. Following this watershed event, armed conflicts within the Tendai sect became chronic, transforming temples into militarized fortresses. However, this phenomenon was not unique to Mount Hiei alone; rather, it reflected broader societal trends. Prominent temples across Japan—such as Kofuku-ji and Todai-ji in Nara, and even Koyasan and Kumano in Wakayama—similarly organized armed groups consisting of lower-ranking monks and peasants from their temple domains.

The historical process behind the militarization of monks is complex and multifaceted. However, key points include not only aristocratic corruption but also the difficulty of imperial intervention, given the temples’ proclaimed role as spiritual protectors. Furthermore, temples such as Enryaku-ji and Koyasan, located deep in mountain regions distant from urban areas, could secretly conduct military training unnoticed by imperial authorities.

Through these intertwined factors, specific temples commanding militant monks ultimately achieved overwhelming authority, engaging in fierce conflicts with rival religious institutions. As the chaotic era of militant monks persisted, the imperial court, weakened and desperate, had no choice but to rely increasingly on the once lower-status warrior class (samurai). Thus began a major historical transition, shifting power from aristocrats to temples and finally to samurai warriors. This development paved the way for the rise of the Taira clan, symbolized by Taira no Kiyomori (1118–1181), whose ascendancy marked the dawn of Japan’s warrior-dominated golden age.

タグ: Monastic Warriors, Sohei, Heian Japan, Samurai Rise, Enryaku-ji, Tendai Sect, Buddhist Militancy, Taira Clan, Imperial Power, Feudal Transition