According to the Old Book of Tang, at the time that that history was compiled, the old records were missing as to her family origins or how she entered the palace.
[3] However, according to the New Book of Tang, she was from Danyang (丹楊, in modern Nanjing, Jiangsu), and her surname might have been originally Erzhu (爾朱).
[4] After Li Qi was defeated and executed in 807,[5] she was confiscated and taken into the imperial palace, where she became a servant girl of Emperor Xianzong's wife Consort Guo.
[4] At some point, Emperor Xianzong had sexual relations with Lady Zheng, and she gave birth to the 13th of his 20 sons, Li Yi.
Her activities during this time were not recorded in history, although it was said that, in 846, her younger brother Zheng Guang (鄭光) dreamed of a wagon bearing the sun and the moon, and six lighted candles uniting into one.
[3][8] It was said that Emperor Xuānzong served his mother in a filially pious way, and because she did not want to reside anywhere else, she remained at his Daming Palace.
[11] Played by Mary Hon, a fictionalized version of Empress Dowager Zheng was portrayed in 2009 Hong Kong's TVB television series, Beyond the Realm of Conscience.