What is the origin of "armor was in power, and there was Mulan Guiying in ancient times"?

If this sentence should be the armor of Mulan, Mu Guiying should tell the story of Mulan first. According to the description of the northern folk song "Mulan Ci" (polished by literati in Sui and Tang Dynasties after the northern Wei moved its capital to Luoyang), there are two main folk sayings about the historical age of Mulan: the first is that during the Taizu period of the northern Wei Dynasty, Mulan joined the army as her father and participated in the war of breaking softness in the northern Wei Dynasty. Mulan's second statement is that during the reign of Emperor Yangdi Yining, Turks invaded the frontier, and Mulan disguised herself as a man and joined the army instead of her father. She fought in the battlefield for many years and made many meritorious deeds. Mulan Ci is a popular folk song in the Northern Dynasty, which lacks close relationship with the Sui Dynasty. This statement at the end of Sui Dynasty was in conflict with the full text in many places, but somehow it spread. ) In the Tang Dynasty, Mulan was posthumously named "General Filial Piety" and was commemorated in a shrine. Hua Mulan's deeds have been handed down to this day, mainly due to the swan song of the northern folk song Mulan Ci. This is a long narrative poem compiled by Guo Maoqian in Song Dynasty, praising the legendary story of Mulan disguised as a man and joined the army as her father. When Mu Guiying ruled the Northern Song Dynasty, Xixia invaded this territory. She Taijun, who retired, heard the news and sent his great-grandson Yang and his great-granddaughter to Bianjing to inquire. Yang Zhan fought in tinker, and Wang Lun, the son of the Minister of War, returned with a handsome seal. Mu deeply felt that the court was unkind and unwilling to work for it. She Taijun advised her to resist the invasion of Xixia, and Mu took command.