in 104 BC. From this point until the end of Western Han, the court established a new era name every four years of an emperor's reign. By Eastern Han there was no set interval for establishing new era names, which were often introduced for political reasons and celebrating auspicious events. Regents and empress dowagers At times, especially when an infant emperor was placed on the throne, a regent, often the empress dowager or one of her male relatives, would assume the duties of the emperor until he reached his majority. Sometimes the empress dowager's faction—the consort clan—was overthrown in a coup d'état. For example, Empress Lü Zhi (d. 180 BC) was the de facto ruler of the court during the reigns of the child emperors Qianshao (r. 188–184 BC) and Houshao (r. 184–180 BC). Her faction was overthrown during the Lü Clan Disturbance of 180 BC and Liu Heng was named emperor (posthumously known as Emperor Wen). Before Emperor Wu died in 87 BC, he had invested Huo Guang (d. 68 BC), Jin Midi (d. 86 BC), and Shangguan Jie (上官桀)(d. 80 BC) with the power to govern as regents over his successor Emperor Zhao of Han (r. 87–74 BC). Huo Guang and Shangguan Jie were both grandfathers to Empress Shangguan (d. 37 BC), wife of Emperor Zhao, while the ethnically-Xiongnu Jin Midi was a former slave who had worked in an imperial stable. After Jin died and Shangguan was executed for treason, Huo Guang was the sole ruling regent. Following his death, the Huo-family faction was overthrown by Emperor Xuan of Han (r. 74–49 BC), in revenge for Huo Guang poisoning his wife Empress Xu Pingjun (d. 71 BC) so that he could marry Huo's daughter Empress Huo Chengjun (d. 54 BC). Since regents and empress dowagers were not officially counted as emperors of the Han dynasty, they are excluded from the list of emperors below. List of emperors Below is a complete list of emperors of the Han dynasty, including their personal, posthumous, and era names. Excluded from the list are de facto rulers such as regents and empress dowagers. Timeline Legend: denotes Western Han monarchs denotes Han monarchs following the collapse of the Xin dynasty but prior to the Eastern Han denotes Eastern Han monarchs See also Dynasties in Chinese history List of Chinese monarchs Notes Footnotes References . External links Chinese History - Han Dynasty 漢