The reason is that the value of Dunhuang Mogao Grottoes was first discovered by foreigners, and the fine products inside were sold by China people to foreign countries at low prices.

Historical background:

In the 26th year of Guangxu (A.D. 1900), Wang, the director of Dunhuang Mogao Grottoes (also known as Thousand Buddha Cave), happened to find a cave in the north of Cave 16, so he excavated the later world-famous Cave of Tibetan Scripture (now called Cave 17).

At the beginning of the cave opening, there were about 40,000 volumes of ancient manuscripts and prints in the cave. The earliest book was written in the middle of the 4th century (Southern and Northern Dynasties), and the latest book was written in 1 1 early century (Song Dynasty), with a time span of nearly seven centuries. In fact, these documents are the first-hand historical materials of politics, economy, culture, religion and life in China in the Middle Ages, and can be described as an encyclopedia of social life in China in the Middle Ages, so they are highly valued by international academic circles. Chen Yinque called this brand-new academic field "Dunhuang studies". These 40,000 volumes of Dunhuang suicide notes include Buddhism, Taoism, Manichaeism and Nestorianism, Confucian classics, literary works (poetry, prose, lyrics, vernacular novels, folk fu, etc. ), local government and temple archives (including folk contracts, social culture, farmland documents, tax books, etc. ), historical and geographical documents, scientific and technological documents (arithmetic, mechanics, metrology, metallurgy, etc.). In addition to Chinese manuscripts, there are a large number of documents written in ancient Tibetan, Uighur, Khotan, Sogdian and Sanskrit. In addition, there are many artworks, including silk paintings, linen paintings, paper paintings, textiles, embroidery, wood carvings and so on. As we all know, after the discovery of the Sutra Cave, a large number of documents and cultural relics were subsequently lost or lost. British Hungarian Stan took about 15,000 volumes. The Frenchman Beriott brought about 6600 volumes; Japan's Zuicho Tachibana, Yoshikawa Koichiro and Russia's Odenburg also took away many papers. Today, there are only more than 8,000 pieces left, which are kept in the National Library. Most of the paintings, textiles, wood carvings and other collections in the cave were taken away by Stan and Pelliott. After taking away a large number of Dunhuang documents and cultural relics, foreigners attached great importance to their value in the study of medieval history, so they seriously carried out the study of Dunhuang studies. There has long been a saying in Japanese academic circles that Dunhuang is in China and Dunhuang studies is in Japan.

This is the historical background of the sentence "Dunhuang scholars are the sad history of Chinese academics".