Sima Guang seems to feel very embarrassed about this contradictory record in Hanshu when compiling Zi Tong Zhi Jian. Therefore, he adopted the method of avoiding expressing the problem directly. When describing Wei Qing's conquest of Henan land, he did not explain which counties were set up locally, but described in the following that Emperor Wu of Han followed his father Yan's plan and began to send troops to Henan land in order to reclaim farmland on Henan land and solve the problem of difficult supply of rations in the northwest.
Sima Guang handled it this way because what Zhu said about Henan reclamation was actually only in the Hetao area of Inner Mongolia where Shuofang County was located. Other areas have poor agricultural conditions and are not suitable as agricultural bases to solve the food ration problem. Wuyuan county is on the edge of Hetao area, even if it is established at the same time as Shuofang, it has little to do with this matter. So this narrative form is actually just a clever way to avoid the contradictory records in Hanshu.
Contemporary scholars are not as cautious about this issue as Sima Guang. Most of them think that Wuyuan County in the Western Han Dynasty was established at the same time as Shuofang County in the second year of Yuanshuo, which means that the establishment of Jiuyuan County in Qin Dynasty was revoked at the end of Qin Dynasty and the beginning of Han Dynasty. This view has become the mainstream knowledge in the field of historical geography in China. Meng Tian died, the vassals rebelled against Qin, China was in chaos, and people who moved to the frontier were all returned. As a result, the Xiongnu relented and returned to Henan a little bit, which was banned by China.
The so-called "old fort", that is, the old frontier fortress, refers to the border at the beginning of Qin's unification of the six countries. Due to the lack of literature, it is not clear where this "ancient fortress" used to be located. Fortunately, the names of roads in the early Han Dynasty listed in Zhang Jiashan's Han bamboo slips "Two-year Laws" provide important information for solving this problem. According to the two-year method and rank method of Zhang Jiashan's Han bamboo slips and other documents, we can not only confirm that this "old castle" was set at the foot of Yinshan Mountain in Qin and Han Dynasties, which is now Wulashan-Daqingshan, but also confirm that Jiuyuan County of Qin Dynasty was inherited from Jiuyuan County of Zhao during the Warring States Period.
After the retreat of the border guards at the end of Qin Dynasty, the border defense line was the northern border defense line of Zhao State during the Warring States Period, and Jiuyuan County was only a small part of the territory of Zhao State's original border defense line. It was not until the year of Yuanshuo that Wei Qing launched a large-scale counterattack against Xiongnu that the old border of Qin people was restored, and a large part of it was the homeland of Jiuyuan County in the former Qin Dynasty. This is the geographical background of the establishment of Shuofang County by Emperor Wu of the Han Dynasty and the renaming of Jiuyuan County as Wuyuan County.
The establishment time of Wuyuan County and the actual situation of the change of its jurisdiction are completely consistent with Lv Zuqian's exposition, and Lv Zuqian's ability to distinguish such complicated administrative divisions is directly related to his familiarity with the geographical situation and geographical settings, in addition to his profound knowledge of general history. Looking at Lv Zuqian's Theory of Six Dynasties and Ten Dynasties, we can see that he is familiar with the dangers and interests of various places; Reading Lu Shi's book with assistant minister Li Renfu, we can know that he also directly participated in the examination and approval of National History Geography when he was in the history museum.
All these indicate that Lv Zuqian has the basic knowledge necessary for geographical textual research. From a purely technical point of view, geographical textual research is a kind of difficult historical textual research because of its strong professionalism. As can be seen from the textual research results of the time when Wuyuan County was founded, Lv Zuqian has superb historical textual research ability, and his interpretation of some historical events is not under Sima Guang. There are many examples of similar textual research results solving problems in memorabilia. Therefore, Lv Zuqian is not only a profound Confucian scholar, but also should occupy a place in the development history of historical textual research and textual research.