In 1377, Zhu Yunjiao was born in Yingtianfu, and in 1392, the crown prince Zhu Biao died of illness, Zhu Yuanzhang made Zhu Yunjiao the emperor's grandson, and in 1398, Zhu Yunjiao, who was only 21 years old, succeeded to the throne and changed the Yuan Jianwen. The young emperor was shy and lacked experience in governing the country, and his talent was far inferior to Zhu Yuanzhang's, and even inferior to those uncles who were brilliant and ambitious. Emperor Jianwen was introverted, lacking self-confidence and strength, and lacking iron-fisted means. However, Emperor Jianwen advocated Confucian education and advocated benevolent political state. During his reign, he vigorously advocated strengthening the status of civilian officials and their role in state politics, lenient punishment of prisons, and severe punishment of eunuchs; on the other hand, he advocated the reform of some of Zhu Yuanzhang's maladministrations, which historians call this period the "New Deal for Jianwen.".
In 1398, Emperor Jianwen began to weaken the power of the feudal states and vigorously suppressed the kings of various regions. The five powerful clan kings were abolished, and Zhu Di, the king of Yan, became the next target of Emperor Jianwen, and the king of Yan was also the most powerful one and the most difficult one for the imperial court to solve. Therefore, Emperor Jianwen was quite cautious in the way he suppressed the Yan King. In August 1399, the King of Yan raised an army in the fiefdom, under the banner of "Qing Jun's side", "Jingnan", known in history as the "Battle of Jingnan". A bloody military confrontation between the imperial court and the Yan king began, which lasted three years. At the beginning of the rebellion, the Yan king did not yet have the advantage in military strength. His army consisted of only one hundred thousand men; he was not able to control any territory other than his fiefdom of Beijing. The Jianwen court in Nanjing, with a standing army three times that of the Yan king's army, had the economy of the whole country, and had abolished several feudal states. However, King Yan's leadership ability and high-quality army were not comparable to Zhu Yunjiao. As the war lengthened, the shortcomings of the imperial court's improper command, weak troop strength, and internal laxity seriously affected the war situation. Until the defeat and retreat, many generals surrendered to the King of Yan.
On the morning of June 13, 1402, Zhu Di, the King of Yan, sent heavy troops to attack the outskirts of Nanjing. Emperor Jianwen was besieged inside the city. After a fierce battle, the Yan army surged into the city like a tide and burned down the palace. King Yan then sent people to search for the remains of Emperor Jianwen. But only the scorched corpse of Empress Ma was found. The King of Yan, fearing a comeback of Emperor Jianwen, searched around internally on the one hand, and sent Zheng He and Hu to look for traces of Emperor Jianwen on the other hand.
When people lost faith in the search for Emperor Jianwen, 37 years later, in 1440 (the fifth year of Emperor Yingzong's orthodoxy), a ninety-year-old monk who lived in a temple in Tianzhou, Guangxi, claimed to be Emperor Jianwen. The King of Yan then took him back to Jingshi and lived in Daxinglong Temple. After seeing the monk, Wu Liang, a eunuch who had served Emperor Jianwen, reminisced about the past and hanged himself after returning home. Then, the Yan King was confident that Emperor Jianwen had not fled, so why did Xingshi move the crowd to look around? Why did a monk who was over nine sentences old dare to risk meeting the King of Yan?