2. There are historical facts contained within the ballad
Incidents are described in the ballad which took place in 429 CE, when Emperor Taiwu of the Northern Wei launched an expedition against the Rouran. They occurred in what is now Mongolia. The Northern Wei established garrisoned forts in an effort to defend their frontier from the Rouran, whom they considered barbarians. The history of the Northern Wei Dynasty is recorded in the Book of Wei, written between 551 and 554 CE. The text tells of the expedition launched in 429, including references to Black Mountain (Shahu Mountain) and Yanran Mountain (Khanghai Mountains) both located within Mongolia. The Ballad of Hua Mulan refers to both.
Though the incidents of the campaign sung of in the ballad are confirmed in the Book of Wei, there is no reference in that record of Hua Mulan. Another record of the Northern Wei Dynasty, a compilation known as Exemplary Women, which covers the period of the ballad, likewise does not mention Hua Mulan. Official records of the period thus do not verify the historicity of the adventures of the legendary woman warrior. The ballad and the folk tales which developed from it remained more or less the story of Mulan for several centuries. Then its retellings began to take on the attitudes of the society in which the tale was retold, with altered aspects of women and their roles in Chinese society.