The method is not correct. It is not the word "all". In fact, most of them changed their names after they ascended the throne.
As for why the names were changed, let's first look at the list of emperors of the Northern Song Dynasty
1. Song Taizu Zhao Kuangyin (unnamed)
2. Song Taizong Zhao Kuangyi first changed his name to Zhao Guangyi and then changed his name to Zhao Jiong
3. Song Zhenzong Zhao Dechang came to the throne and changed his name to Zhao Heng
p>4. Song Renzong Zhao Youyi came to the throne and was renamed Zhao Zhen
5. Song Yingzong Zhao Zongshi came to the throne and was renamed Zhao Shu
6. Song Shenzong Zhao Zhongzhen came to the throne and was renamed Zhao Xu ,
7. Song Zhezong Zhao Ji ascended the throne and changed his name to Zhao Xu
8. Song Huizong Zhao Ji (unnamed)
9. Song Qinzong Zhao Quan or Zhao Xuan After ascending the throne, he changed his name to Zhao Huan
It can be clearly seen that not all of them have two words, most of them were actually changed after ascending the throne.
The first question, why did Song Taizong Do you want to change your name from Zhao Kuangyi to Zhao Guangyi first? In fact, anyone who is slightly familiar with history knows that the "taboo" with Chinese characteristics is to avoid the emperor's name and replace it with homophones (re-reading found that there is a problem here, the taboo also reduces the emperor's name and adds one stroke). Therefore, if everyone in the Song Dynasty did not change their names, then words such as De, Chang, Shou, Yi, Zong, Shi, etc. are actually common names. Occasionally, one or two founding emperors were too domineering and did not change their names. Most emperors in history After he came to the throne, his name would be changed, and there were only a few who did not change his name (this rule was broken by the Ming Dynasty, but another rule, which was to try to choose uncommon words, was still retained). It would be fine if the two characters Kuangyin were not commonly used. If every emperor does this, I'm afraid there are not many commonly used characters left in Chinese naming, so it is actually a tradition for the emperor to change his name to a single character with a rare character after he ascends the throne.
In addition, the names of the emperors of each dynasty also had their own characteristics. Xia and Shang began to use Tiangan, and Liu to Tang did not use the same radicals before and after. The Song Dynasty's favorite use of "日" in their names directly influenced the Jin Dynasty (most of them also had the word "日" Wan Yan Min Wan Yan Sheng Wan Yan Dian Wan Yan Jing Wan Yan Xun Wan Yan Shouxu)
Golden Wood of the Ming Dynasty Everyone knows about water, fire and earth