Empress Dowager Li Ezi , later Buddhist nun name Changbei , was an empress dowager of the /Xianbei dynasty Northern Zhou. She was the mother of .
Li Ezi was born in 536, around the Jiangling region, then ruled by Liang Dynasty. In 554, Northern Zhou's predecessor state Western Wei's general Yu Jin launched a major attack on Jiangling, then the capital of Liang's , capturing it and killing Emperor Yuan. While Western Wei then declared Emperor Yuan's nephew Liang's emperor , to be a vassal of Western Wei, when Yu withdrew, he captured most of the population of Jiangling and the surrounding region back to the Western Wei capital Chang'an as spoils of war. Western Wei's paramount general Yuwen Tai awarded Li Ezi to his son , then the Duke of Fucheng, to be Yuwen Yun's concubine. She was seven years older than Yuwen Yong.
After Yuwen Tai's death in 556, his son took the throne from Emperor Gong of Western Wei in 557, ending Western Wei and establishing Northern Zhou as its Emperor Xiaomin. As the emperor's brother, Yuwen Yong continued to carry the title of duke, although he was promoted to the Duke of Lu by another brother, , who succeeded Emperor Xiaomin after the powerful regent Yuwen Hu deposed and killed Emperor Xiaomin later in 557. In 559, Lady Li gave birth to Yuwen Yong's oldest son .
In 560, Emperor Ming was poisoned by Yuwen Hu, and Yuwen Yong became emperor . He created Yuwen Yun the Duke of Lu. He did not create Consort Li empress, and immediately began overtures to pursue formal marital relations with Tujue, commencing in marrying the of Tujue's Mugan Khan, Ashina Qijin in 568 as his empress. However, Empress Ashina did not bear a son, and in 572, after Emperor Wu killed Yuwen Hu and personally took power, he created Yuwen Yun crown prince. In summer 578, Emperor Wu died, and Yuwen Yun became emperor . He honored both Empress Ashina and Consort Li as empress dowagers .
In spring 579, the erratic Emperor Xuan formally passed the throne to his young son , and he took an atypical title for a retired emperor -- "Emperor Tianyuan" . He thereafter changed her title several times -- to ''Tianyuan Di Taihou'' in spring 579, then ''Tian Huang Taihou'' in summer 579, and ''Tianyuan Sheng Huang Taihou'' in spring 580. In summer 580, Emperor Xuan died, and Emperor Jing, then under the control of the regent , honored both Empress Dowager Ashina and her as grand empress dowagers -- but with the title ''Tai Di Taihou'' to distinguish her from the greater title of ''Tai Huang Taihou'' that Empress Dowager Ashina carried.
In 581, Yang Jian seized the throne from Emperor Jing, ending Northern Zhou and starting Sui Dynasty . Emperor Jing and other members of Northern Zhou's imperial Yuwen clan were soon slaughtered. Grand Empress Dowager Li became a Buddhist nun, and changed her name to Changbei. She died in 588, and was buried only with ceremony due a Buddhist nun, south of Chang'an.