In the 21st century BCE, Xia Qi established China's first slave-owning state, the Xia Dynasty, which lasted over four hundred years and saw seventeen rulers. The final ruler, King Jie, was cruel and debauched, oppressing the people and exhausting their labor, leading to barren fields and a populace barely able to survive. The people of Xia hated him deeply, wishing to perish together with him. Jie gradually lost all support, becoming utterly isolated and abandoned.
At this time, a tribe called Shang was growing increasingly powerful. The founder of the Shang tribe was named Qi. When Yu the Great was controlling the floods, Qi assisted him and made great contributions, so Shun granted him the land of Shang to govern. After more than four hundred years of development, by the end of the Xia Dynasty, the fourteenth leader of the Shang tribe was named Tang. Tang was a ruler who worked hard to govern well. He showed kindness to his tribal people, valued agriculture, and built irrigation projects, which ensured abundant grain and a growing population. At the same time, he encouraged trade and promoted commerce, greatly increasing social wealth. Just as the Xia Dynasty's rule was declining, the Shang tribe, under Tang's leadership, gradually became a powerful tribe.
Jie was debauched and tyrannical, causing the state's internal governance to fall into disrepair, external threats to arise incessantly, and the people to become alienated and disloyal. Tang, seeing the nation trapped in such a dire situation, was deeply worried, and so recommended the virtuous and talented sage Yi Yin, who was at his side, to Xia Jie.
Yi Yin was one of the most important ministers in the early Shang Dynasty. His original name was Yi Zhi, with "Yin" being an official title. In oracle bone inscriptions, he is referred to as Yi, while in bronze inscriptions, he is called Yi Xiaochen. Legend has it that Yi Yin was abandoned as an infant in a mulberry forest, where he was found and adopted by the Youxin clan living near the Yi River, and thus took Yi as his surname. Yi Yin was short in stature and plain in appearance. As an adult, he made a living by farming and held a lowly status. However, he was intelligent and diligent, concerned about the world's affairs, and harbored lofty ambitions. He enjoyed studying the governance principles of ancient sage-kings and carefully observed society, conducting deep analyses of the current situation. He realized that the Xia Dynasty's fate was exhausted and that only a wise ruler could rise to replace it. Seeing that the ruler of the Youxin clan was a virtuous man, he wanted to persuade him to raise the banner of righteousness and launch a campaign to overthrow the Xia. But the ruler was far above him and not easily accessible, so he voluntarily became a slave and was presented to the Youxin ruler. Later, due to his exceptional culinary skills, he became the Youxin ruler's personal chef. The Youxin ruler discovered Yi Yin's great talent and promoted him to the position of Baozheng, overseeing the kitchen. Through observation, Yi Yin realized that the Youxin clan were also descendants of Xia Yu, sharing a close bloodline with the Xia royal house, making it difficult for them to rise against the Xia. Moreover, the Youxin state was too weak to destroy the Xia Dynasty.
Later, Tang married a daughter of the Youshen clan as his consort. Yi Yin believed that Shang Tang was a man destined for great things and had long intended to join him, so he seized the opportunity of Tang's marriage to the Youshen clan to volunteer as a dowry slave, accompanying her to Shang and becoming Tang's cook. Wanting to present his ideas on governing the state, he used Tang's inquiries about food as an opening, employing cooking and the five flavors as a metaphor to weave the principles of statecraft into the process of preparing dishes, while also analyzing the state of the world and arguing that the Xia Dynasty was unjust and should be overthrown.
Tang then realized that the chef beside him was a man of great talent and grand vision, immediately freed him from slave status, and treated him with great respect. Tang recommended Yi Yin to Xia Jie, and Yi Yin went to the capital of the Xia Dynasty, where he met Xia Jie and tried to influence him using the benevolent governance of the ancient sage-kings Yao and Shun, hoping to guide him to abandon evil, embrace good, care for the people, and rule the world with kindness. However, Xia Jie completely ignored him, let alone gave him any important position. Seeing that his talents were of no use there and staying was pointless, Yi Yin returned to Tang's side.
After Yi Yin returned, Tang officially appointed him as the Right Prime Minister. With Yi Yin's assistance, Shang Tang focused his main efforts on developing agriculture, casting weapons, and training the military. Soon, the Shang state became more prosperous and flourishing, and its national strength grew even more powerful.
Later, Jie, the last ruler of the Xia Dynasty, built the Qing Palace and the Yao Terrace to please his favored concubine Mo Xi, causing the people to suffer bitterly, and the minister Guan Longfeng was killed for his frank remonstrance. At that time, everyone was as silent as cicadas in winter, with no one daring to speak another word. However, Tang of Shang quickly sent someone to the Xia capital to mourn Guan Longfeng. The growth of Shang had already aroused Jie's vigilance, so he seized this opportunity to accuse Tang of disregarding the king's authority, ordered his arrest, and imprisoned him in the Xia Tower (located in present-day Yuzhou, Henan). The ministers of Shang were panic-stricken, and the people were deeply worried about their ruler. At this critical moment, it was Yi Yin who took charge. He knew Jie well, understanding that Jie was a man addicted to wine and women, surrounded by sycophantic villains. Thus, Yi Yin gathered rare treasures and beautiful women to present to Jie, while bribing Jie's trusted close ministers to speak well of Tang. Sure enough, Tang was soon released and returned to Shang.
After returning to Shang, Tang felt that Xia Jie was so corrupt and incompetent that he could not govern the realm at all, thus strengthening his resolve to raise an army to destroy Xia and take over. With the assistance of Yi Yin, Tang of Shang accelerated his plans to overthrow Xia. When Tang believed the time was ripe to launch an attack on Xia, Yi Yin advised him to first stop paying tribute to Xia Jie and observe his reaction before deciding whether to send troops. As a result, Xia Jie flew into a rage and ordered the Nine Yi tribes to mobilize their forces to attack Shang. Yi Yin said, "Now that Xia Jie can still command the armies of the Nine Yi, this is not the time for us to strike." So, Tang of Shang feigned an apology to Jie, resumed tribute payments, and while waiting for the right moment to attack, intensified efforts to strengthen his own power.
After a year had passed, Shang Tang once again stopped paying tribute to Jie, but this time the tribes of the Nine Yi, dissatisfied with Jie's oppression, had already rebelled against the Xia Dynasty and refused to follow Jie's orders. Yi Yin said, "Now is the time to attack Xia Jie!"
Thus, Tang gathered his soldiers and officers for a solemn oath-taking ceremony before launching the campaign against the Xia dynasty. With impassioned fervor, he declared that the tyrant Jie of Xia was cruel and unjust, causing immense suffering to the people, and that he himself was now acting on Heaven's mandate to overthrow the Xia. He urged everyone to unite their efforts and topple the corrupt Xia dynasty. The words Tang spoke at this oath ceremony were recorded by the official in charge of documents, and that record became the "Oath of Tang" in the Book of Documents.
Tang, riding his horse across the battlefield, first destroyed the Ge state, then annexed over a dozen small vassal states and tribes of the Xia Dynasty. He led his troops to break through the stronghold states of Wei and Gu, which were allies of Jie, and defeated the Kunwu state. As a result, with the Shang capital Bo as the center, the Shang territory expanded to a vast area spanning several hundred li. Following this, Tang led the allied states toward Mingtiao, the key stronghold of the Xia Dynasty, to attack the Xia capital.
The Shang army quickly approached the Xia capital, and the people of Xia, who had long wanted to overthrow the tyrant Xia Jie, cheered and responded enthusiastically upon hearing of the Shang attack. Xia Jie, now panicked and abandoning his revelry, hastily assembled his troops, and the two sides clashed in a great battle at Mingtiao (present-day east of Kaifeng Qiu, Henan). The Shang soldiers were exceptionally brave and unstoppable, while the Xia troops, unwilling to fight for the cruel ruler Xia Jie, were demoralized and many fled the battlefield, making them vulnerable and quickly routed. Seeing his army collapse like a landslide and unable to turn the tide, Jie fled in panic into the city, then broke out with Mo Xi and treasures. The Shang army pursued relentlessly, and Jie escaped on a small boat across the river to Nancao (present-day Chaozhou, Anhui), where he later died.
Shang Tang achieved a complete victory, then unified the entire realm and ascended to the throne. He implemented a series of benevolent governance measures, and all the feudal lords willingly submitted to his rule, bringing an end to the Xia Dynasty, which had reigned for over four hundred years.