Studies on the Buddhism of Kutcha makes the Dinggu mountain where the Kumtula Grottoes is located a keyword in contemporary researches. After going through the modern materials about the Western Regions, the article points out Hening, an official served in the Western Regions of the Qing Dynasty, was the one worthy of more attention. It's Hening who mistook Liuzhong of the Turfan Basin a place of Kutcha when compiling Huijiang Tongzhi (lit. Chorography of Xinjiang), and then mistook the Dinggu mountain of Luchen in Xichui Jilue (lit. Brief History of the Western Border Area) dated the early Qing Dynasty as the mountain Qol-Tag near the Kumtula Grottoes. Such misunderstanding was persisted by Qi Yunshi and Xu Song, and the authority of Xu's famous work Xiyu Shuidao Ji (lit. River Systems of the Western Regions) makes people believe easily the Dinggu mountain was in Kutcha. To sum up, as a Chinese placename, the Dinggu mountain is actually a previous name of Toyoq in the Turfan Basin.
