(Chinese: 固原; pinyin: Gùyuán), formerly known as Xihaigu (Chinese: 西海固; pinyin: xīhǎigù, Xiao'erjing: قُ‌يُوًا شِ), is a prefecture-level city in the Ningxia Hui Autonomous Region of the People's Republic of China. It occupies the southernmost section of the region, bordering Gansu province to the east, south, and due west. This is also the site of Mount Sumeru Grottoes (须弥山), which is among the ten most famous grottoes in China. As of the end of 2018, the total resident population in Guyuan was 1,124,200.