18 Grand Historian said

A1.26|27

From the Yellow Emperor to Shun and Yu, they all had the same surname Gongsun, but they had different national titles in order to highlight their respective virtues. Therefore, Huangdi the Yellow Emperor was titled Youxiong, Emperor Zhuanxu was titled Gaoyang, Emperor Ku was titled Gaoxin, Emperor Yao was titled Taotang, and Emperor Shun was titled Youyu. Emperor Yu, who started Xia, also stated the tradition of using a different surname, Si. The Situ Qi, whose name 契 had the literal meaning of the contract, was the ancestor of Shang and surnamed Zi. And the Sinong Qi, whose name 弃 had the literal meaning of the abandonment, was the ancestor of Zhou and surnamed Ji.

Taishigong the Grand Historian said: "The Five Emperors had been talked about by many scholars, it had been around since ancient time.  While Shangshu the Ancient Book recorded historical facts only since Yao; and the descriptions of the Yellow Emperor by each school were rough and not typical, and it has been difficult for the scholars and officials to explain clearly. There were books named "Zaiyu Asks the Virtues of the Five Emperors" and "Emperors’ Lineage & Surnames" handed down by Confucius. Many scholars might have not passed them on. I had gone to Kongtong in the west, Zhuolu in the north, the sea in the east, and had crossed the Yangtze River and Huai River in the south. Wherever I went, the seniors there often talked about what they had heard. The deeds, the customs and the teachings of Huangdi, Yao and Shun were all different. In general, I think those statements, that are consistent with the records in ancient scriptures, are close to be accurate, I have studied the books "Spring and Autumn" and "Guoyu the State Language", and the related book volumes and chapters of "Five Emperors Virtues" and "Emperors’ Lineages & Surnames", and found that they are very clear and no need to dig any deeper, and that their descriptions are not false. "Shangshu" may has been incomplete for a long time, but scattered anecdotal records can often be found in many other books. If not good in learning and used to in-depth thinking, even if you truly understand its meaning in your heart, it will definitely be difficult to explain it to those whose knowledge are shallow and limited. I reviewed and sorted these materials, selected those whose words were particularly elegant, recorded them, and wrote this journal, which is listed as the beginning of this book.”

自黄帝至舜、禹，皆同姓而异其国号，以章明德。故黄帝为有熊，帝颛顼为高阳，帝喾为高辛，帝尧为陶唐，帝舜为有虞。帝禹为夏后而别氏，姓姒氏。契为商，姓子氏。弃为周，姓姬氏。

太史公曰：学者多称五帝，尚矣。然尚书独载尧以来；而百家言黄帝，其文不雅驯，荐绅先生难言之。孔子所传宰予问五帝德及帝系姓，儒者或不传。余尝西至空桐，北过涿鹿，东渐于海，南浮江淮矣，至长老皆各往往称黄帝、尧、舜之处，风教固殊焉，总之不离古文者近是。予观春秋、国语，其发明五帝德、帝系姓章矣，顾弟弗深考，其所表见皆不虚。书缺有间矣，其轶乃时时见于他说。非好学深思，心知其意，固难为浅见寡闻道也。余并论次，择其言尤雅者，故著为本纪书首。