Overview
Cheng Tang (born Zi Lü), recorded on oracle bones as, in English, Tai Yi (太乙) or Da Yi (大乙), was the first king of the Shang dynasty. Traditionally considered a virtuous ruler, as signified with the common nickname of "Tang the Perfect" given to him. According to legend, he overthrew Jie, the last ruler of the Xia dynasty.
Rise of Shang
Tang ruled Shang, one of the many kingdoms under the suzerainty of the Xia dynasty, for 17 years. During Jie's reign, Shang grew in power, initially at the expense of Xia's other vassals. He was able to win many supporters from as many as 40 smaller kingdoms. Tang recognized that Jie mistreated his people and used this to convince others. According to legend, in one speech, Tang said that creating chaos was not something he wanted, but given the terror of Jie, he had to follow the Mandate of Heaven and use this opportunity to overthrow Xia. As an advantage he pointed out that even Jie's own military generals would not obey his orders.
In the 15th year of Jie's reign, Tang began moving Lü to the capital Bo. About two years later Shang sent his minister Yi Yin as an envoy to Jie. Yi remained in the Xia capital for about three years, before returning to Shang.
The Shang's power continued to grow. In the 26th year of Jie's reign, Shang conquered Wen. Two years later, Shang was attacked by Kunwu, and several years of war between Shang and Kunwu followed. Despite this setback, Shang continued to expand on a number of fronts, gathering vassal troops in Jingbo. The Shang army and allied forces conquered Mitxu (today's Xinmi in Henan), Wei, and attacked Gu, which too was conquered the following year. About this time Zhong Gu, chief historian of Jie, would flee from the Xia to the Shang.
From Wikipedia (CC BY-SA 4.0).