Shortly after Li Fangyuan acceded to the throne, it was for Emperor Taizong of Korea. Li Fangyuan, Emperor Taizong, sent so-called "greetings" to Xianxing many times in order to find out the truth of his father, but these greetings were all shot dead by Emperor Taizong. There is a vivid record in Korean history books: "After the change, Shang (Mao) abandoned his post and fled to Xianxing. Emperor Taizong sent envoys to meet him many times, but he bowed his head and waited. Before and after the relative envoys, dare not look. ..... when greeting makes no one get it. Taizong asked his ministers,' Who can be sent?' No one answered. "Visible at that time, the sharp opposition of emperor taizong and his son.
Nevertheless, Emperor Taizong strongly invited Taizu to return to Beijing. Junlin of Changning House is an old friend of Taizong. Emperor Taizong thought that Emperor Taizong would definitely listen to him, so he sent him to Xianxing to meet him. When Cheng Shiyi arrived in Xianxing, he said, "Ride a white horse with clothes on, if you pass by, dismount and light a fire, if you cook." The Maoists sent a eunuch to inquire about the situation. Cheng Shiyi told him that he was going on a long trip and hoped to spend the night. The eunuch told Mao when he got back, so he could make an exception and see Mao. Later, when Cheng told him about his return to Beijing, Mao immediately flew into a rage and said, "Nothing is to soothe your cheeks?" Cheng Shizhen argued: "If so, the descendants of the minister will be blind!" Taizong believed his words and returned to Seoul (Taizong moved his capital back to Seoul after he acceded to the throne). Later, Cheng's descendants really became blind.
But in November of 1402 (the second year of Taizong), Taizu went to Xianxing again, and no one dared to "say hello". So Judge Park Chun stepped forward and went to Xianxing. He accompanied his mother and son with two horses. Park Chun came to a tree in front of Li Chenggui, tied the mare to the tree, and led the mare to move on. The mare and mare are reluctant to go, and the scene of screaming is just witnessed by Li Chenggui. Later, Mao called and questioned, and Park Chun hoped to move Mao. Mao knew what he meant and was very unhappy, but he stayed with him. One day, Mao was playing with Park Chun, and a mouse happened to hide in a corner with its cub until it died. When Park Chun saw it, he "fell to the ground and cried, which was beneficial to beheading it." Mao said, "Stop talking and let me think." So he told him that he would return to Beijing. Park Chun is gone. After Park Chun left, the minister close to Mao asked to kill him. Mao didn't agree at first, and it is estimated that he won't agree after Longxing River. So Taizu gave the sword to the messenger and said, "You have crossed the river, so don't chase it." However, Park Chun suddenly fell ill on the way. At this time, he went to the river, the messenger came and cut off his waist. When Mao heard about it, he regretted it very much and "decided to go back to the south".
However, Mao later seemed to go back on his word and still had no intention of returning to Beijing. Li Fangyuan was at the end of his rope, so he had to turn to his father Li Chenggui's best friend, the ignorant master. Li Chenggui had a deep friendship with Wuxue, and finally Li Chenggui agreed to return to Seoul from Hamhung. In this way, Li Fangyuan, Emperor Taizong of North Korea, took great pains to sacrifice the lives of many messengers sent to Xianxing, and finally made Emperor Taizong Li Chenggui leave Xianxing.