The Baoxie Trail, the Shimen Tunnel, and its cliff inscriptions

　　I. The Baoxie Trail

　　In the Qinling Mountains, there is a valley that cuts through the Guanzhong Plain and leads into the Hanzhong Basin. Its southern mouth is called Bao, located about 25 kilometers north of present-day Hanzhong District, and its northern mouth is called Xie, situated 15 kilometers southwest of Meixian County, stretching a total length of 235 kilometers. Since the Warring States period, people have been carving through rocks and erecting wooden trestles to build plank roads in this valley. Successive dynasties continued this effort with multiple expansions, and later generations named it the “Baoxie Trail.” Emperor Wu of the Han Dynasty significantly expanded the Baoxie Trail over a span of 250 kilometers, leading to the grand scene of “a thousand li of plank roads, connecting everywhere without obstruction.”

　　II. The Shimen Tunnel

　　The Shimen Tunnel is an artificially excavated tunnel located at the southern mouth of the Baoxie Trail. It is 16.3 meters long, 4.2 meters wide, and 3.45 meters high. In 1970, during the construction of the Shimen Reservoir, it was submerged underwater.

　　According to the “Inscription of Shimen,” the tunnel was excavated during the Eastern Han Dynasty, around the 1st century AD. Hence, a modern foreign expert once remarked, “The world’s earliest artificially excavated mountain tunnel is located in Baocheng, Shaanxi, China.” This refers to the Shimen Tunnel.

　　Since the Qin and Han Dynasties, the Shimen Tunnel has experienced periods of being open and blocked, with numerous restorations over time, many of which left behind cliff inscriptions.

　　III. The Cliff Inscriptions of Shimen

　　Inside the eastern and western walls of the Shimen Tunnel, as well as along the perilous slopes, cliffs, riverbeds, and large rocks on the beaches for several miles to the north and south of the tunnel, there are numerous cliff inscriptions dating from the Han Dynasty to the Song Dynasty. Some record the construction and restoration of the Baoxie Trail, the Shimen Tunnel, and the Shanhe Weir project through the ages, while others are commemorative inscriptions left by visitors and travelers. A Qing Dynasty count identified approximately 40 types. Among them, the “Thirteen Masterpieces of the Han and Wei Dynasties” gained fame as early as the Tang and Song Dynasties and enjoyed nationwide renown.

　　The so-called “Thirteen Masterpieces of the Han and Wei Dynasties at Shimen” refer primarily to the Eastern Han Dynasty’s “Inscription of Shimen” carved on the eastern and western walls inside the tunnel and the Northern Wei Dynasty’s “Inscription Commemorating the Opening of Shimen,” with the former being especially renowned. The “Inscription of Shimen” has long been famous throughout the country and is a treasure for studying ancient Chinese transportation history and the history of calligraphy art. Its calligraphy, in particular, is a masterpiece of “Han clerical script.”

　　Due to the construction of the Shimen Reservoir, the Shimen cliff inscriptions were relocated and reassembled in 1970 to the Ancient Han Platform in Hanzhong City. A dedicated room was built for them, named the “Exhibition Hall of the Thirteen Masterpieces of the Han and Wei Dynasties at Shimen.” It attracts a continuous stream of domestic and international visitors.