Why isn't Mulan surnamed Hua?

Mulan's surname, native place, etc. There is no record in the history books, so the dispute between Mulan has always existed throughout the ages.

Mulan's native place was first mentioned by He Chengtian (370-447) at the end of the Eastern Jin Dynasty and the beginning of the Southern and Northern Dynasties. In his book "The Family Name Garden", he said that Mulan was a city dweller. He thought Mulan's surname was Mu, which came from Duanmu Ci, a disciple of Confucius. Duanmu changed his surname to Mu to avoid retaliation. Zigong was originally from Shandong, that is, Qufu. During the Eastern Jin Dynasty and the Southern and Northern Dynasties, Qufu belonged to Rencheng County, and He Chengtian called Mulan a Rencheng native, but this was not recognized by the academic circles.

At present, the most controversial places are Bozhou, Anhui, Yucheng, Henan, Huangpi, Hubei and Yan 'an, Shaanxi. Yucheng was changed from Niangniang Temple to Mulan Temple, and later belonged to Mulan's hometown. Huang Bei called Mulan Mountain with Mulan tree, built Mulan Temple, and later attached to Mulan's hometown; Yan 'an is more than a hundred miles west of the Yellow River, or you can "say goodbye to your parents and stay by the Yellow River at dusk", where there is a Wanhua Mountain, which is also attached as Mulan's hometown. All the above three places believe that Mulan came from Sui Dynasty or Tang Dynasty. As we all know, "Mulan Ci" was circulated among the people in the Han Dynasty, and it was also compiled into "Ancient and Modern Music Record" by wise craftsmen in the Southern Dynasty. How did Mulan appear after the Northern and Southern Dynasties?