Since Tang Gaozu Li Yuan founded the Tang Dynasty in Chang'an, the emperors ascended the throne in Chang'an City. However, in the generation of Li Heng of Emperor Suzong of Tang, he changed the rules and went to Ningxia to ascend the throne as emperor.
During the Tang Tianbao period, Emperor Xuanzong Li Longji favored Yang Guifei and was extravagant and corrupt. Soon the traitorous minister Yang Guozhong took control of the imperial government, and the emissaries in various places saw that Tang Xuanzong was so relaxed, and they all grew their own strength. Jiedu made an anthonymity the most ambitious of the subordinates.
In 755, the three towns of Fanyang, Hedong, and Lulong made An Lushan raise an army against the Tang under the name of Yang Guozhong, and proclaimed himself emperor of the State of Great Yan in Luoyang. Soon after, tongguan was breached. Tang Xuanzong immediately fled from Chang'an with his concubines and his entourage. When they arrived at Ma Songpo, there was a mutiny, and Yang Guozhong and Yang Guifei were killed one after another.
The person who planned this incident was The Crown Prince Li Heng. When Emperor Xuanzong fled, he ordered the crown prince Li Heng to lead a large army to break the queen. In addition to two-thirds of the troops who fled this time, Li Heng's men also had forbidden troops. Li Heng felt that he had been the prince for too long and had to do something big. From the moment he left the Beijing Division, Li Heng was thinking about the mutiny.
By the time they reached Ma Songpo, the soldiers were already hungry and thirsty, and the army began to stir. Li Heng felt that the time had come, and sent his confidant eunuch Li Fuguo to woo the general Chen Xuanli of Zuo Longwu, and in the end, Li Heng and his cronies reached an agreement and started an incident. He sent the Forbidden Army to kill Yang Guozhong, as well as his wife and children. However, killing Yang Guozhong was only the first step in the incident, and the real killing had just begun.
Forcing Yang Guifei to kill was another step in Li Heng's conspiracy to mutiny ma song. Li Heng had his subordinates play Xuanzong with the fact that Yang Guozhong had been killed, and stated yang Guozhong's heinous crimes, and then had the soldiers force Xuanzong to kill Yang Guifei. As soon as Yang Guozhong died, the strength of the court was the greatest among the princes, and his spearhead was directed at Xuanzong.
However, to Li Heng's surprise, Chen Xuanli, as the leader of the Forbidden Army, took the lead in expressing his allegiance to Xuanzong after executing the noble concubine. This ensured Xuanzong's personal safety, and Li Heng felt that this was very unfavorable to himself, in case Xuanzong found himself after himself to settle the account. Thinking about it, Li Heng decided not to flee west with Tang Xuanzong, so that he could save himself.
So he came to Shuofang (朔方, in present-day Ningxia) and ascended the throne as emperor, honoring Emperor Xuanzong as Emperor Taishang. Emperor Suzong of Tang dispatched troops and generals in Lingwu, commanded the world, quelled the rebellion, and revived the Tang Dynasty, and the Ningxia region also became the base of the Tang Dynasty's strategic counterattack.