yearnames

Yearnames, also called era names or nengō, are labels assigned to spans of years within a calendar to identify the period. They are typically chosen to reflect auspicious wishes, major events, or the reign of a ruler. In many historical calendars, years are counted within an era starting from 1 rather than by consecutive calendar years.

In China, the era-name system (nianhao) was used for much of imperial history. An emperor might adopt a new era name to mark a campaign or a new phase, and multiple era names could occur within a single reign. Each era has its own year numbering, so Kangxi 1 marks the first year of the Kangxi era. The system largely faded after 1912, when the Republic of China adopted the Gregorian calendar. Examples include Kangxi (1662–1722), Guangxu (1875–1908), and Xuantong (1909–1912).

In Japan, the system is known as nengō. The era name changes with the accession of a new emperor or other ceremonial reasons, and years are counted from 1 within each era. Meiji began in 1868; later eras include Taishō (1912–1926), Shōwa (1926–1989), Heisei (1989–2019), and Reiwa (2019–present). Public dates are often written as the era name plus the year, such as Reiwa 5, which corresponds to 2023.

Other uses include the Minguo calendar in Taiwan, where Minguo 1 equals 1912 and is used alongside the Gregorian year in official contexts. In monarchies, regnal years count the years of a ruler’s reign. Today, yearnames are mainly of historical or cultural interest in most places, with the Gregorian calendar serving as the standard for everyday dating.