After the demise of Guo Xu, the descendants of the imperial clan took Xu as their surname, which was called authentic in history. The Xu family continued to grow and develop, forming counties such as Runan, Levin, Henan, Huiji and Taiyuan. Xu is the county of Levin, so Xu is called Levin's.
Ancient records:
"A Brief History of Clans": "Xu, surnamed Jiang, is the ancestor of Qi. After Emperor Yan, Yao Siyue was also the son of Boyi. He named his Miao-born uncle Wen Xu, thinking that after Taiyue, it is today's Xuzhou. From Uncle Wen to Duke Zhuang, I saw the Spring and Autumn Period. In the first year of Yuan Gongzi's marriage, he got the age of Lin. "
Textual research on the surname quotations in "Surname Yuanyun", which also said: "Xu, Jiang surname, Boyi was the same clan as Qi after four days. Sun Yu Xu was named, and later generations took the country as their surname. " Xu Gucheng is now Xuchang, Henan.