Octagonal Ancient City in Gannan Secret Land

The Octagonal Ancient City is located 35 kilometers north of Xiahe County, on the plateau where Yangqu River and Yangla River in Gannan Prairie meet. The Octagonal City is named for its eight corners, and the city outline is a hollow cross. This place was a key point of transportation in ancient Gansu and Qinghai, and it was also a military stronghold fiercely contested by the central authorities and the Tuyuhun, Tubo, Xixia, and Siro dynasties. Archaeological surveys have proven that the Octagonal City preserves a large number of cultural relics from different periods such as the Northern and Southern Dynasties, Sui, Tang, Song, Yuan, Ming, and Qing, which also explains the rise and fall history of the Octagonal Ancient City on the ancient Silk Road.