A Chinese era name (traditional Chinese: 年號, simplified Chinese: 年号, pinyin nían hào) is the era name, reign period, or regnal title used when traditionally numbering years in an emperor's reign and naming certain Chinese rulers (see the conventions). Some emperors have several era names, one after another, where each beginning of a new era resets the year back to one or yuán (元). The era name originated as a motto or slogan chosen by an emperor.
Emperor Wu of Han China (Han Wudi) was conventionally regarded as the first emperor to declare an era name; however he was only the first to use an era name in every year of his reign. His grandfather and father also employed era names, though not continuously. Han Wudi changed period titles every five years or so, going through a total of eleven reigning slogans during his reign from 140 BC to 87 BC.
Each era name has a literary meaning. For instance, the first era name of Han Wudi was Jianyuan (建元 in pinyin: jian4 yuan2), literally meaning "establishing the First". Era names also reflected charateristics of political and other landscapes at the time. Jianzhongjingguo (建中靖國 jian4 zhong1 jing4 guo2), the first era name of Emperor Huizong of Song China, means "establishing a happy medium and cleansing the country", reflecting his idealism towards moderating the rivalry among the conservative and progressive parties on political and social reformation. The very first era name of the Qing was significant because it means "[the Manchus possess] the Mandate of Heaven".
The process of era name declaration was referred to in traditional Chinese history texts as jianyuan. Declaring a new era name to replace an old one during an emperor's reign was referred to as gaiyuan (改元 gai3 yuan2), literally meaning "change the First".
To name a year using an era name only requires counting how many years the year in question is after the first year of the era. For example 138 BC was the third year of Jianyuan (建元), since 140 BC was the first year. When more than one monarch used the same motto, the name of the specific monarch or dynasty has to be mentioned. For instance both Han Wudi and Jin Kangdi picked Jianyuan as their motto. Thus 344 AD was the second year of Jianyuan of the Jin Dynasty (or of Jin Kangdi) whereas 139 BC was the second year of Jianyuan of the Han Dynasty (or of Han Wudi). In traditional literature, one can therefore find references like "the first month of the thirteenth year of Jianyuan" (建元十三年元月).
An era name could only be declared by the emperor before the Republic of China was established. It was thus a symbol of imperial power. Declaration of another era name when one was in use was regarded as a challenge to the current emperor. The existence of more than one era name at a time often reflected political unrest. In addition, using a particular era name was a political act implying recognition of a sovereign's right to rule, and one issue that traditional Chinese historians faced was which set of era names to use when dating a historical event.
Almost all era names have exactly two characters. Notable exceptions are from the non-Han Chinese Western Xia Dynasty (1032 - 1227). Of the 33 Western Xia era names, seven have more than three characters. For example,
- Tiansilishengguoqing (天賜禮盛國慶 tian1 si4 li3 sheng4 guo2 qing4) (1070) "Heaven-given ritualistic richness, nationally celebrated"
- Tianshoulifayanzuo (天授禮法延祚 tian1 shou4 li3 fa3 yan2 zuo4) (1038) "Heaven-instructed rituals and laws, perpetually blessed"
Modern history researchers do not care about era names except for supporting other arguments, such as figuring out the biases and attitudes of a particular historian; however such mottos are useful for dating events since they were unique in Chinese history. Most Chinese dictionaries have a comprehensive list of era names, while booklets of more detailed and often searchable lists can be found in libraries.
Emperors from the Tang Dynasty up to but not including the Ming Dynasty are better identified by their unique temple names. Ming Dynasty and Qing Dynasty emperors are known by their era names, because during these two dynasties the practice was to choose only one motto for the whole reign.
A fuller description of this naming convention is given in the Chinese sovereign entry.
Era names were also employed (under different naming conventions) in other East Asian countries such as Korea, Japan and Vietnam, mostly because of China's cultural influence. They are still used in Japan. In addition, Taiwan occasionally uses Minguo (i.e. the Republic), which can be regarded as an era name.
- Comparative historical timlines and era names of China, Japan and Korea (in Japanese) (http://homepage1.nifty.com/history/history.html)