nianhao

nianhao, literally “year designation,” is the Chinese term for the era name system that was used by Chinese emperors to mark the years of their reigns. The practice began during the late Western Zhou period and was formalized in the Qin dynasty, when emperor Qin Shi Huang declared a single era name for his entire reign: Qin Shi Huang. By the Han dynasty, it became customary for each emperor to select one or more era names, often reflecting auspicious meanings such as "Wuying" (無懿) or "Tianhe" (天河). The era name was listed on official documents, stelae, and coinage, and the years of a given era were counted from the first year of that name. For example, the year 65 CE in the Chinese calendar was the 15th year of the "Yongyuan" (永元) era of Emperor Guangwu.

The nianhao system remained in use throughout imperial China, with each emperor having the authority to adopt an era name at the start of their reign or at significant events. Some emperors used multiple era names during a single reign to commemorate major campaigns or to signal a new phase of governance. The tradition extended to the various Chinese kingdoms and vassal states during the Three Kingdoms, Jin, and Southern and Northern Dynasties periods. The era name convention was finally abolished with the Qing dynasty’s fall in 1912, replaced by the Gregorian calendar.

In modern Chinese historiography, the nianhao is a key chronological marker. Scholars rely on era names to date ancient documents with precision, and many historical works are organized by the era names of their subject emperors. The term also appears in discussions of Chinese literature, where era names contextualize dynastic settings and influence literary styles.