What does "Japan" mean? Why did Japan change its name?
"Japan" means the place where the sun rises. In the third year of Emperor Yang Di's great cause (607), Sister Xiao Ye presented Shoto Kutaishi credentials to Emperor Yang Di. There is a famous saying: "Japanese people originated from the son of heaven, and there is no son of heaven in the book, so they are innocent". She claims to be of "Japanese descent" and "Japan" is also a Chinese word. At first, it refers to the place where the sun rises.
Before becoming an official country name, "Japan" sometimes even referred to the Korean Peninsula or Bohai State. According to "Biography of New Tang Dynasty Japan", in the first year of Xianheng (670), Japan sent an envoy to the Tang Dynasty, and the envoy said, "It was named because it was recently published." The word may have spread from the Korean peninsula to Japan.
As for why Japan changed its name, it is related to Japanese national sentiment. After all, Japan is far from the mainland, and it doesn't respect China like North Korea, Vietnam and other countries. It prefers to be associated with Tang Dynasty. Whether it is "Japan" or "Yamato", if it is pronounced as "Wa", it is named by China people, so it is officially called "Japan".