Tongwan (in modern Yulin, Shaanxi), forcing the Xia emperor Helian Chang to flee to Shanggui (上邽, in modern Tianshui, Gansu) and allowing Northern Wei to take more than half of Xia territory. In 429, Emperor Taiwu commissioned Cui to continue writing Northern Wei's history, a project that had started under Emperor Daowu with the official Deng Yuan (鄧淵) in charge. Cui engaged Deng Yuan's son Deng Ying (鄧穎) to assist him. This project, however, would eventually have dire consequences for both Cui and Deng. Also in 429, at the advice of Cui, and against the advice of all other officials and his wet nurse Nurse Empress Dowager Dou, Emperor Taiwu attacked Rouran. (Cui believed that further major conflicts with Liu Song were inevitable, and that Northern Wei must first deal Rouran a major defeat to avoid being attacked on both sides.) However, Cui did not accompany Emperor Taiwu on this campaign, although he did inform Kou, who was, that the main Rouran force must be found and destroyed. When Emperor Taiwu engaged Rouran and dealt it a major loss, but was unable to find its Mouhanheshenggai Khan, Yujiulü Datan, he did not want to advance any further in fear of a trap, and even when Kou informed him what Cui had said, he stopped the pursuit. Only later did he find out that he was actually close to Yujiulü Datan's position and could have easily found and destroyed Yujiulü Datan, and he regretted this greatly. Around this time, for Cui Hao's contributions, Emperor Taiwu awarded him several high titles. Cui often observed the stars at night, and he soaked copper in vinegar. Whenever he would see something unusual, he would use the copper as a pen and write his findings on paper. Knowing this, Emperor Taiwu often visited Cui's house at night to consult him, and despite Cui's inability to serve him with gourmet food, Emperor Taiwu would often eat at least some of the food that Cui offered before returning to his palace. When new vassals, Gaoche chiefs, arrived in Pingcheng, he introduced Cui Hao to them, with this commentary: When you see this man, he looks thin and weak, unable to bend bows and unable to bear spears. However, the power in his heart is greater than a million soldiers. Often, I have desire to conquer but not the resolution to do so, and I am able to