According to the records in Ming history, the emperor possessed Zheng He, formerly known as the Prince of Yan, and went to Kyoto to launch a mutiny, becoming the ancestor of the emperor and changing his country name to Yongle. Hui Di, who was usurped at that time, became a monk and fled overseas. He died of a sudden illness, but his body is gone. Cheng Zu was always restless, so he appointed Zheng He to visit overseas. This is the most familiar reason. According to Zhou Yusen's book Zheng He's Route Examination, it was initially said that the failure of Hui Di, a beggar sect, was also due to the decrease of vassals. This reform actually abolished the king's fief and relief rights, thus consolidating the central government. Because of its fierce nature, it led to the Jingnan Incident, Yan entered Beijing, left, and Fang Xiaoru and other cronies took over one after another. Hui Di was isolated, so his whereabouts were erratic. Then Cheng Zu continued to climb the big fort, sent a large number of eunuchs to search for the trace of Hui Di, and sent Zheng He to command tens of thousands of sailors and expedition for tens of thousands of miles, which lasted for decades without any danger. Is this large-scale military operation just to find the long-lost Hui Di? However, Gai Chengzu's desire to visit outsiders and my passionate kiss are actually forces that can endanger the national defense of the Ming Dynasty. This kind of power was already a serious problem in the early Ming Dynasty, so Zheng He was sent to command the boatmen and took the opportunity to destroy them in the name of visiting Hui Di.

Another reason is that after the demise of the Yuan Dynasty, a westerner appeared. Bois collected the historical data of Asia at that time and wrote a book "The Biography of Timur Empire", which introduced in detail that after the defeat of the Yuan Dynasty by Ming Taizu, it was divided up by the Yuan Dynasty in West Asia, and the situation was very chaotic. A wife, Xu Timur, was promoted to Samarkand and became a direct relative of Genghis Khan. They unified this situation by force during the Hongwu period. Seven years after the collapse of Ming Taizu, they declared war on the Ming Dynasty at the Samarkand Conference.

The third reason is that Japan was called a slave country in ancient times and later renamed Japan. He often came to the coast of China to harass and plunder, and was known as the enemy in history. Until the sixth year of Hongwu, Ming Di was most indignant. Due to the extremely long south coast of China and poor defense, the enemy took advantage of it, robbed and plundered, killed and set fire to everything. If the defense is tight, the enemy will turn to the South Island to recuperate. Therefore, Ming Di ordered Zheng He to go to the Western Seas, boarded a treasure ship with more than 20,000 soldiers, and went out to sea to subdue the enemy, which was also one of the reasons.