At present, there are the following statements.
The first is the theory of the Northern Wei Dynasty; That is, during the period of Emperor Wu of the Northern Wei Dynasty, Mulan joined the army as her father and took part in the battle of breaking Rouran in the Northern Wei Dynasty.
It is said that around the 5th century AD, the northern part of China was in the ruling stage of the Northern Wei Dynasty, and the nomadic people in the north were constantly plundering south, which made the people in the Central Plains uncomfortable. So in order to solve the border problem, the court decided to recruit soldiers to fight. At that time, it was stipulated that each family should send a man to the front. However, Mulan's father was too old and sickly to go to war, and her younger brother was still young, so Mulan decided to join the army instead of her father and began her military life for more than ten years.
The second is the Sui and Tang Dynasties. That is, during the reign of Emperor Gong of Sui Dynasty in Yining, the Turks invaded the frontier, Mulan disguised herself as a man, joined the army on behalf of her father, fought in the battlefield for many years, and made many meritorious deeds.
It is said that at the end of the Sui Dynasty, the Central Plains stood side by side, and the world was in chaos. Turkic Khan, who had surrendered to the Sui Dynasty, took the opportunity to get rid of the control of the Sui Dynasty and conquered everywhere. According to "Tongdian Turkic", "from Qidan in the east to Tuguhun and Gaochang in the west, all of them fell, and the string was controlled by one million, and the soldiers prospered."
At that time, Mulan joined the army with Dou Jiande. Because Dou Jiande established Xia Guo, Dou Jiande was also considered as an emperor. At that time, Dou Jiande established political power in the north and was threatened by the northern Turks. The king of Turkey is called Khan. When the Turks attacked Dou Jiande, Dou Jiande organized troops to resist the Turks, and Mulan joined the army at this time. In the battlefield 12 years, she made many meritorious deeds, but no one found out that she was a woman. After returning to the DPRK, it was named Shangshu. In the Tang Dynasty, he was named "General Filial Piety" and was commemorated in a shrine.
I prefer the first statement, that is, Mulan came from the Northern Wei Dynasty!
First of all, in Mulan Ci, there are poems such as "Khan gives many soldiers" and "Go to see the son of heaven, and the son of heaven sits in the court". This shows that the monarch of Mulan is a person with dual identities of Khan and emperor. During the Northern and Southern Dynasties, the Northern Dynasty in northern China was founded by Xianbei people, who would call the ruler Khan. Of course, the official name of the Northern Wei Dynasty is the emperor, but because of tradition, people may still call it Khan! Mulan Ci happens to be a folk song, so it is not surprising to call it Khan. ("Shu Wei Xu" records that "when Emperor Wen was in office, he was forbidden to sweat")
Secondly, there are several place names in Mulan Ci, including "Going to Montenegro at dusk" and "But I heard that Yanshan is chirping". Among them, Montenegro kills Hushan, which is in the southeast of Hohhot, Inner Mongolia, not far from the Yellow River. Yanshan Mountain refers to Yanran Mountain, that is, today's Mongolians and the State Bank of Ai Shan. This shows that the war in Mulan's poems happened between the Northern Wei Dynasty and Rouran.
Rouran, also known as creepy, Rui Rui, Ru Ru, creepy, etc. China is a minority in the north, probably active in the Southern and Northern Dynasties. In 402 AD, Sharon was established as the autumn capital of Fahan, and the soft khanate was established. Rouran khanate often used troops to seize the needed food and materials, which became a great threat to the Northern Wei Dynasty.
In the 5th century AD, a protracted war broke out between the two countries. For more than 20 years, Rouran attacked the northern border of the Northern Wei Dynasty almost every year. The Northern Wei Dynasty also sent troops to the Northern Expedition, and even marched or patrolled the border in person, and strengthened the reclamation and set up military towns along the border, stationed heavily and guarded Pingcheng. Tuoba GUI, the great emperor of the Northern Wei Dynasty, made seven separate attacks in the process of destroying Xia Lian, Beiyan and Beiliang.
The main battlefields between the two countries are Montenegro and Mount Yanran. In 429, Emperor Taizu of the Northern Wei Dynasty made a moderate northern expedition, that is, "driving out of the house and heading for Montenegro" and "there is Yanran in the north and three thousand miles in the north and south".
In addition, according to Mulan Ci, it is unbelievable that Mulan has been in the army for more than ten years and her daughter has never been found. However, in the Northern Wei Dynasty, in order to resist the gentle invasion, the Northern Wei Dynasty specially set up six towns around Pingcheng. Mulan, as a border guard, may have her own residence in the town. If she had nothing to do, she would have gone to war as soon as there was a war, so she was not found disguised as a man.
To sum up, Mulan may come from six towns in the Northern Wei Dynasty, and the object of her father's attack in the army may be Rouran.
Finally, it is worth mentioning that the folk song "Mulan Ci" was first recorded in the Record of Ancient and Modern Music compiled by the shaman wise craftsman in the Southern Dynasties, in which the monk wise craftsman said, "Mulan is nameless." This shows that Mulan lived in an era no later than the Northern and Southern Dynasties and the Chen Dynasty. Combined with the historical background at that time, the war Mulan participated in should be the war between the Northern Wei Dynasty and Rouran.