Shimen is a section of tunnel at the southern end of Baoxie plank road, which was excavated in Yongping period of the Eastern Han Dynasty. The excavation process of the tunnel was engraved on the cliff in the form of words. Shimen is the first man-made tunnel in the world. In the sixth year of Yongping in the Eastern Han Dynasty (66 years), it was built by burning water. It occupies an important position in the ancient traffic history of China. The opening of Shimen and the precedent of rock climbing have inspired the feelings of literati in the past dynasties. On the east and west walls and cliffs on both sides of the Baohe River, there are a large number of inscriptions and notes since the Han and Wei Dynasties. There are only 34 stone carvings on the inner wall of Shimen, plus stone carvings on the north and south cliffs of Shimen and river stones, totaling 104. These stone carvings in Shimen are precious stone carving books, especially the Han and Wei stone carvings, which are rare in China. For this reason, the stone gate of Baoxiedao and its cliff carvings were identified as the first batch of key cultural relics protection units in China in 196 1.

From 1969 to 197 1, due to the construction of water conservancy facilities, the state had to move the most admired 13 cliff stone carving in the reservoir flooded area to Hanzhong Museum. These stone carvings and calligraphy works are called "Thirteen Stone Gates" and are known as "national treasures". These calligraphy works are called "products" because the words are carved on stone tablets.

Thirteen products of Shimen occupies an important position in calligraphy art and gives people the enjoyment of the beauty of calligraphy art. It is the highest artistic crystallization of paying equal attention to calligraphy and seal cutting since the Han Dynasty. Among them, the works of the Han and Wei Dynasties were well-known in the world as early as the Tang and Song Dynasties, and were highly praised by archaeologists and calligraphers in previous dynasties. At present, thirteen pieces of Shimen are important objects for studying Han Li, and enjoy a high reputation in calligraphy and epigraphy at home and abroad.