Why is the Tiantishan Grottoes renowned as the progenitor of Chinese grottoes?

If you mention Wuwei, do you only think of it as the excavation site of the 'Flying Horse of Gansu', a symbol of Chinese tourism? In fact, in Wuwei, there lies the Tiantishan Grottoes, which scholars call the 'progenitor of Chinese grottoes'. It is one of the earliest grottoes carved in our country and represents early grotto art. Although the painted surfaces of the Buddha statues have long faded and the stone sculptures are mostly damaged, it still stands quietly here, telling the rise and fall of history to the world. No matter the season or time, when you visit Wuwei, you must not miss the Tiantishan Grottoes. Whether you want to appreciate the charm of the grottoes up close or seek a rare moment of tranquility in your heart, this place can satisfy all your desires. The Tiantishan Grottoes, also known as the Great Buddha Temple, are located in Dengshan Village, Zhangyi Town, 50 kilometers south of Wuwei City, founded during the Northern Liang of the Eastern Jin and Sixteen Kingdoms period, with a history of about 1600 years. The peaks of Tiantishan are majestic and steep, soaring high into the clouds, with stone steps on the mountain. Climbing up the steps, the path is rugged, resembling a hanging ladder, hence the name Tiantishan. The main attractions of the Tiantishan Grottoes include the Tiantishan Grottoes Exhibition Hall, the Arhat Cave, and the Great Buddha Cave. Walking 200 meters from the entrance of the scenic area, you can reach the Exhibition Hall, and another 200 meters past the Exhibition Hall will take you to the Arhat Cave. The niches on both sides of the passage in the Arhat Cave display the eighteen Arhats, each with a different pose, lifelike in appearance. Now, only three levels of the Tiantishan Grottoes remain, with a total of 18 caves of various sizes. The largest cave has a remaining height of 30 meters, a width of 19 meters, and a depth of 6 meters. Inside the cave, there is a statue of Sakyamuni Buddha, with Manjushri and Samantabhadra Bodhisattvas, the Heavenly Kings of Wide Eyes and Many Ears, and the six statues of Kasyapa and Ananda on both sides of the Great Buddha, all vividly modeled and dignified in appearance. The Great Buddha sits against the wall, with his left hand on his knee and his right hand raised to shoulder height, palm facing outward, in the gesture of fearlessness. Following the steps on both sides, you can reach the foot of the Great Buddha. Looking up at the silent Buddha, only the wind howls past the side of the mountain...