During the Three Dynasties and the pre-Qin period, nobles had both surnames and surnames, and they coexisted. The rule is to use the surname before the man's name and the surname after the woman's name. Surnames cannot appear in men's names, but only in women's names. For example, many princesses in Qi are called "Qi Jiang". The real names of all Zhao and Qin monarchs who obtained Zhao's surname should be "Zhao", and Qin Shihuang's real name is, not Ying Zheng.
The name "Ying Zheng" neither conforms to the naming rules of men at that time, nor is it a normal female name, neither fish nor fowl! In fact, it existed after the Han Dynasty and was invented by later generations. The reason was that the ancient surname system had died out at that time, and most people didn't understand the surname culture in pre-Qin. People regard ancient surnames as modern surnames mechanically, and apply them directly in front of names, thus creating a bunch of nondescript names such as "Ji Fa", "Jiang Shang" and "Kongdang". Only the historians of the Han Dynasty are most familiar with the ancient surname culture, because they lived very close to the Warring States period and the pre-Qin period. Therefore, they all called Qin Shihuang Zhao Zheng, and would not commit the fallacy of "Ying Zheng". As for the history books of the Spring and Autumn Period and the Warring States Period, the king of Qin was never called "Zhao" because historians could not directly address the monarchs of the same period. The history books of Qin can only be called "king", "majesty" and "emperor", while the history books of other countries at the same time call them "Qin".