Introduction to the three Longmen caves: "Yunzhan Notes" records: "The back of the Dragon Cave is called Longmen Mountain. There is a stone cave dozens of feet high. It is shaped like a door. There is a diving and rushing water in it. The sound is very loud and flows through the belly of the mountain. It is divided into three caves, the second cave flows out of the water, and the third cave flows into the Jialing River from the southwest. "