the four great caves, namely: Longmen Grottoes 龍門石窟|龙门石窟[Lóng mén Shí kū] at Luoyang, Henan, Yungang Caves 雲岡石窟|云冈石窟[Yún gāng Shí kū] at Datong, Shanxi, Mogao Caves 莫高窟[Mò gāo kū] at Dunhuang, Gansu, and Mt Maiji Caves 麥積山石窟|麦积山石窟[Mài jī Shān Shí kū] at Tianshui, Gansu