Emperor Taizong offered sacrifices to Beiyue, praying for the blessing of mountain gods and helping his military operations. Judging from the geographical location of Beiyue, Beiyue occupied an important position in north-south transportation in the Middle Ages. Therefore, compared with the other four mountains, the emperor of the Tang Dynasty had higher requirements for defending the border and consolidating the political power.
most of these sacrifices with military appeal are presided over by officials. In addition to Emperor Taizong's expedition to the Liao Dynasty through Beiyue in the 19th year of Zhenguan, important military ministers also went to Beiyue Temple to offer sacrifices and ask for help. The Tang emperor's sacrifice to Beiyue was also closely related to the ritual of praying for rain and sunshine. Hengshan Mountain in Beishan is a famous mountain and river obviously included in the sacrificial ceremony, and it is the object that must be sacrificed in this area. The sacrifice was presided over by the governor and Shangzuo, which fully reflected the official color of the rain-praying sacrifice in Beiyue.
In June of the 14th year of Kaiyuan (726), Emperor Xuanzong of the Tang Dynasty ordered his officials to sacrifice mountains and rivers because of the long-term drought. At that time, he wrote a performance for Li Zhe, the envoy of Beiyue, and attributed the effect of rainfall to Xuanzong's sincerity. According to the statistics of the inscriptions on the ritual and special sacrifices left over from the Tang Dynasty, from the 9th year of Dali in Tang Dynasty (774) to the 6th year of Xiantong in Tang Dynasty (865), there were 17 special sacrifices in Hengshan, Beiyue. Except for the sacrificial envoys sent by the central government, most of them were presided over by assistants of the Ministry of Justice.
At the same time, there are also sacrificial activities of praying for rain and praying for children in different folk belief classes. At the same time, the worship of Beiyue God and the activities of praying for rain are also carried out in different folk belief classes. The reason why the emperors in Tang Dynasty attached so much importance to and even worshipped Mount Hengshan in Beiyue was related to their worship of Taoism.
For emperors, on the one hand, it is because the fasting ceremony of Taoism can pray for the blessing and misfortune of the rulers and the peace of the world; Taoist alchemy and health-preserving prescriptions can satisfy the wishes of emperors and nobles for eternal life. More importantly, Li Tang used Taoism to create a legal basis for his imperial power. During the Sui and Tang Dynasties, although the gentry rule that prevailed since the Wei and Jin Dynasties declined, the social status and influence of gentry were still great. The royal family in the Tang Dynasty came from a humble military family in North Korea, not a famous family.
At the end of the Sui Dynasty, Li Yuan, Li Shimin and their sons sent troops to fight for hegemony in the world. In order to improve their status and win the support of the upper class nobles, and taking advantage of the coincidence that Lao Zi, the founder of Taoism, was surnamed Li, they respected Li Er as the ancestor of the king of the Tang Dynasty. They should call themselves immortal Miao descendants in order to create a public opinion that "God grants imperial power". In order to win the support of the new rulers for Taoism, some Taoists also created the so-called "performance of the old king" and granted religious myths and prophecies "Fu Ming" to meet the needs of the royal family in the Tang Dynasty.