The Yulin ("Forest of Elms") Grottoes, aka Wanfo Xia ("Gorge of Ten Thousand Buddhas"), is situated on the banks of the Yulin River about 75 kilometers south and slightly east of the city of Anxi, or about 100 kilometers east and slightly south of Dunhuang. The Yulin Grottoes, whose 1000-year construction spanned the Northern Wei (CE 386-533) to the Qing (CE 1644-1911) Dynasties, is placed under the administrative auspices of the same organization that oversees the management of the main two cave complexes near Dunhuang, the Mogao Grottoes and the Western Thousand Buddhas Caves.
The most interesting thing about the Yulin Grottoes is that they contain works belonging to the Western Xia (CE 1038-1227) Dynasty, aka the Tangut Empire, which ruled the area of present-day Gansu Province and Ningxia (Ningxia Hui Autonomous Region) in the period CE 1038-1227 (the Tanguts were called the Dangxiang in Chinese), and whose capital was the ancient city of Lingzhou (the city of Yinchuan in present-day Ningxia), which they renamed to Xingqing fu.
The Yulin Grottoes complex comprises 42 surviving grottoes cut into the walls of sheer cliff faces on either side of the Yulin River, only a few of which caves, alas, are in a good state today. Caves 2 and 3 of the cave complex belong to the Tangut period, and thus provide invaluable insights into the art and culture of these Qiangic (Tibeto-Burman) speaking Turkic nomads (of Xianbei/ Manchurian origin, aka the Monguor, or "White Mongols", a reference to their pale complexion) who would roam the Ordos Desert, which desert stretches across parts of Inner Mongolia (Inner Mongolia Autonomous Region) and Ningxia, as well as parts of Gansu and Shaanxi Provinces.
Note that while the Tangut language is related to the language of the Qiang Chinese ethnic minority, one of 55 such minority groups recognized in China, the Tanguts actually belonged to a Turkic ethnic group, the Xianbei, who moved from present-day Russian parts of what was formerly called Manchuria - i.e., from the area farther north and west of present-day northwest China - south and eastward into the northwestern part of present-day China and Mongolia that was at the time occupied by a Qiangic tribe, conquering the Qiangs, absorbing them and in the process, adopting their Qiangic language, though the Xianbei were originally an Altaic-speaking (Turkic-speaking) people (note also that the original, pure Han Chinese, i.e., before they became "corrupted" ethnically speaking, or before they began to conquer and absorb other ethnic groups, were themselves members of the Qiangic ethnic family).
The Tanguts espoused a form of Buddhism that repesents a hybrid mix of Chinese and Tibetan Buddhism, mixed with elements of animism, or the belief that all things, animate or inanimate, possess a spirit. The source of Tangut Buddhism's scriptures is the Chinese interpretation of Buddhism, translated into the Qiangic language of the Tanguts, though in practice, the Tanguts mixed elements of both the Chinese and the Tibetan interpretations of Buddhism, a development that is not at all suprising, given that the area occupied by the Western Xia Dynasty was formerly ruled by the Tibetans, with Tibetan monks still living and teaching their Tantric (i.e., 'marked by rituals' as opposed to 'marked by meditation') Buddhism in the area when the Tanguts arrived.
Cave number 25 at Yulin is a strictly Tibetan Buddhist cave, with unique murals and other art works in a clearly identifiable "Tibetan style", and is considered the most magnificent of Yulin's existing caves. Cave number 25 stems from the period (CE 781-847) of Tibetan occupation of the greater, Qinghai-Gansu-Ningxia area.
The Yulin Grottoes, given their Tangut contribution to the Buddhist art works of the area - which itself provides an insight into Tangut culture in general, and into the culture of the Western Xia Dynasty in particular - are an important additional building block in our understanding of the religious-cultural dynamics that were at play in Dunhuang during the millenium in question.