Eiman

Overview

Eiman (永万) was a Japanese era name (年号, nengō; literally "year name") that followed Chōkan and preceded Nin'an. The era spanned from June 1165 through August 1166, during the Heian period (794–1185). The reigning emperor during this time was Emperor Rokujō (六条天皇).

The era was short, lasting just over a year. It began in the middle of the twelfth century, a time when the imperial court in Kyoto was increasingly overshadowed by the rising military power of the Taira and Minamoto clans.

What Defined the Era

The Eiman era opened with a change in imperial succession. Emperor Nijō had died in 1165, and his young son, Emperor Rokujō, ascended to the throne. Rokujō was only an infant at the time, so the actual governance of the court fell to his grandfather, the retired Emperor Go-Shirakawa, who exercised authority from his cloistered position.

The era name was changed to mark the new reign and to signal a fresh start. In the Japanese court system, era names were often altered in response to significant events—accessions, natural disasters, or auspicious omens—and the start of a new emperor's rule was one of the most common triggers.

The period was also marked by the ongoing political manoeuvring of the Taira clan, led by Taira no Kiyomori, who was consolidating power at court. The Eiman era saw the continued rise of Kiyomori's influence, setting the stage for the Taira dominance that would define the following decade.

Key Events

The most significant event of the Eiman era was the accession of Emperor Rokujō. He became emperor in the sixth month of 1165, following the death of his father, Emperor Nijō. Because Rokujō was still a child, the retired Emperor Go-Shirakawa continued to hold effective power as cloistered emperor.

In the eighth month of 1165, the era name was formally proclaimed, replacing Chōkan. The change was announced in an imperial edict, a standard procedure for marking a new era.

The era ended in August 1166, when the name was changed again to Nin'an. The reason for this second change is not recorded in the surviving sources, but era changes of this kind were common in the Heian period, often prompted by court politics, natural phenomena, or the desire to reset the calendar.

The Name in Japanese

The era name is written 永万 in Japanese.

• Kana reading: えいまん
• Romaji: Eiman

The name consists of two kanji:

• 永 — read ei (えい) in this word. The character means "eternal" or "long-lasting." It appears in words like 永遠 (eien, "eternity") and 永久 (eikyū, "permanence"). The character depicts flowing water, suggesting something that continues without end.

• 万 — read man (まん) in this word. The character means "ten thousand" and, by extension, "all" or "myriad." It is the same character used in the number 万 (man, ten thousand) and appears in phrases like 万事 (banji, "all things"). In this context, it conveys the idea of vastness or completeness.

Together, 永万 can be understood as "eternal myriad" or "ten thousand eternities"—a name expressing the hope that the era would bring long-lasting peace and prosperity. The choice of such an auspicious name was typical of Heian-era nengō, which were selected to invoke good fortune for the realm.

The reading Eiman follows the standard on'yomi (Chinese-derived reading) for both characters: 永 as ei and 万 as man. This is the conventional way era names are read in Japanese, and it is the reading used in historical records and modern reference works.

How the Era Name Works

The Japanese era name system, known as nengō (年号), dates back to 645 CE, when the first era name, Taika, was proclaimed. The system was modelled on Chinese practice, where emperors used reign titles to mark periods of their rule. In Japan, era names were used to date official documents, legal records, and historical chronicles.

An era name was chosen by the imperial court, typically after consultation with scholars and diviners. The name was usually composed of two kanji, selected for their auspicious meanings. The characters were meant to convey a positive message—peace, prosperity, virtue, or longevity—and to reflect the court's hopes for the years ahead.

Era names could be changed for a variety of reasons. A new emperor's accession almost always prompted a new era, as happened with Eiman. But eras were also changed to mark the beginning of a new sexagenary cycle, to celebrate auspicious omens, or to ward off the effects of natural disasters or epidemics. In some periods, eras lasted only a few months; in others, they endured for decades.

The system remained in continuous use until the Meiji period, when the government adopted the rule of one era per emperor. The modern era, Reiwa, began in 2019 with the accession of Emperor Naruhito. For students of Japanese, understanding nengō is essential, because historical documents, literature, and even modern legal records are dated by era name and year. When reading a text that says 永万元年, it refers to the first year of the Eiman era, which corresponds to 1165 in the Western calendar.