Historically, Japan was a vassal state of China, which began with Emperor Wu of the Han Dynasty. After Emperor Wu of the Han Dynasty proclaimed himself emperor, and after the Han Dynasty attacked the Qin system, the county system was still implemented throughout the country. At that time, Zhang Qian's mission to the western regions failed to contact Dayue's family, but small countries such as Yunnan, Dali and Kunming were found in the southwest border region, which was called "Southwest Yi" (see Sima Qian's Historical Records and Biography of Southwest Yi). Emperor Wu of the Han Dynasty wanted to persuade Canon to submit to the Han Dynasty. King Dian relied on the support of many small countries around him and was very arrogant. But also asked the envoys of the Han Dynasty: "Which is bigger than your Han Dynasty?" Such a ridiculous question. In a rage, Emperor Wu of the Han Dynasty sent troops to wipe out the small countries around Yunnan, and the country of Yunnan lost its trust in the Han Dynasty. Emperor Wu of the Han Dynasty gave Yunnan a golden seal, and the seal was "Wang Yin, Yunnan" of Xiao Zhuan. At the same time, Japan (then called "Japan") was awarded a gold seal-the national seal of Japan. The intention of Emperor Wu of the Han Dynasty was to recognize the existence of the kings of Dian and Japan in the Han Dynasty.

At present, this Japanese seal has been kept in Japan with the number of Japanese cultural relicNo. 1, while the Wang Yin of Yunnan was unearthed in the tomb of Shizhai Mountain in Jinning, Yunnan Province after liberation and kept in the National Museum (formerly the Museum of Chinese History). But the casting is rough and the seal is chiseled out. According to experts' speculation, it should be the tomb instead of the king of Yunnan. It turns out that the golden seal issued by Emperor Wu of the Han Dynasty should have been handed down from the Wang Dynasty in Yunnan, but it has not been found yet. I heard from the teacher of the Social Education Department of Guo Bo that when Japanese experts visited Guo Bo, the first thing they wanted to see was "Yunnan Wang Yin", because it was released at the same time as Japan India, which confirmed the history of Japan.