Sacred temple on the "Big mountain of the South"

Thuong temple, also known as the Spirit Palace, located within the relic of Tan Vien Son, Ba Vi Mountain, is the sacred temple on the "Big mountain of the South".
The entire relic is located in two communes of Minh Quang and Ba Vi, Ba Vi district, Hanoi, worshipping Tan Son Tinh – the most powerful of four the immortal Vietnamese gods. From Ba Vi National Park gate, take the left turn and go about 10km to the gate of Thuong temple. According to the legend and Ngoc Pha (the book of the annals), the temple was built under King An Duong Vuong’s age. The temple is located at the top and is called Tan Vien Mountain or Ngoc Tan Mountain. In his book "Du Dia Chi" (Guide of Geography), national cultural figure Nguyen Trai called it "Big Mountain of the South". To build the Upper Temple, feudal dynasties had to manage a huge size of workers on both sides of the river. According to the legend, the people joined hands to transfer materials from the Da River to Mount Tan to build Thuong temple.
Thuong Temple is located in Mount Ba Vi at 1,227m altitude, in Ba Vi commune. The temple is built in the north-south direction, with a unique architecture, the roof tiles tilting behind the cave entrance, the lower roof erected under a large stone to create a temple with a strong and deep foundation. It is built in a small scale, with only one chamber and no other auxiliary items. In the early years of the 21st century, the monument was restored and has a new appearance as it is today. In the first half of the twentieth century, in the years 1923-1926 C. Madrolle published two important books, Northern Indochina and Southern Indochina. In Northern Indochina, C. Madrolle writes: "On the occasion of the three-year ritual, the worshipers of Tung Thien, Tong Bat raised the prehistorical hammers and bronze hunks picked up at the foot of Tan Vien mountain."
Then, in Les Mường book, geographie humaine et sociologie by French literary scholar Jeanne Cuisinier, published in Paris in 1948, he wrote: "Every three years, people held a ceremony in a temple at the top of the mountain, which was collapsed".
The festivals worshipping The Saint of Tan Vien Son at many temples in Doai (West region) are held simultaneously on January 15th of the Lunar Calendar. According to legend, this is the anniversary of the birth of the Genie. The festival at Thuong temple is held for 3 days from the 14th to 16th of January. The ceremonies as recorded in C. Madrolle's book are no longer celebrated. The main rituals include a feast on the 14th, the procession of water from the Da river to the shrines of worshipping.
On the 15th, 15 villages in Ba Vi and Minh Quang Commune held the procession from the village to the temple, then back from the temple to the village. They offer pig, chicken, rice cake, flowers, and fruits to the gods. On the occasion of the festival, there is also a ceremony at Trung Nghia commune (across the river in Phu Tho province).
Also in the year, at the temple there is a forest closing ceremony, held on December 25.