A rare collection of more than 26,000 ancient Chinese books dating back as early as the tenth century were on display in Peking University's library in Beijing on Saturday and Sunday. Valuable works produced in the Song, Yuan, Ming and Qing dynasties were among the exhibited pieces, said a library spokesman. The exhibits, including works on Chinese philosophy, history, classics and literature, were bought from Japan's Okura Museum of Art in 2013 for 1.8 billion yen (about 17.6 million U.S. dollars), said the spokesman. The university and the government provided the funds for the purchase. In the early 20th century, a cash-strapped Chinese book collector sold part of his collection to Okura Kihachiro, a Japanese entrepreneur and founder of the Japanese museum. Since then, the entrepreneur's company has worked to increase the museum's collection of ancient Chinese books. The collection bought back will be preserved in Peking University's library.