Wanyan Jing's real name is Mada Ge, the grandson of Shizong and the legitimate son of Xianzong Yun Gong. He received Chinese education since childhood and followed Shizong's order to learn Jurchen language and writing. His father died young in 1185, and he was established as the emperor's grandson the following year. He ascended the throne after Shizong's death in the first month of 1189, and changed his name to Mingchang the following year.
Zhangzong was fond of literature, calligraphy and painting, and studied calligraphy in Song Huizong's thin gold style. During his reign, he revised rituals, music, criminal laws and official systems, and promulgated "Taihe Laws and Meanings". Imperial examinations and schools became increasingly prosperous, and it was known as the "Mingchang Rule" in history. He overhauled the border forts in the north, united the Mongolian tribes to conquer Tatar, and repelled the Southern Song's Kaixi Northern Expedition in 1206, forcing the Southern Song to increase their annual coins.
However, in his later years, he doted on Li Shier, the concubine of the Yuan Dynasty, and his relatives and sycophants gained power, and the government gradually deteriorated; the Yellow River burst at Yangwu, the banknotes devalued, and the finances became increasingly difficult. The northern Mongolian tribes were unified during this period, but Jin Dynasty was not alert. Zhangzong died of illness in November 1208, and all his sons died young. He was succeeded by his uncle, King Yongji of Wei.
The Zhangzong era was the peak of Jin Dynasty's civilized rule. Ritual, music, punishment, and government were in full swing. Han culture was deeply rooted in the hearts of the upper Jurchens, and they still had the upper hand in the war against the Song Dynasty. However, as time passed, the clan and Meng'an became increasingly corrupt, relatives and sycophants gained power, excessive banknotes were issued, and the Yellow River breach increased the financial burden; he also lacked foresight for the changes in the northern grasslands. Only a few years after Zhangzong's death, Jin Dynasty declined sharply under the attack of Mongolia.