As for the study of Sanskrit in the Tang Dynasty, we don't know much. The fourth volume of Xuanzang's Biography says: "(Xuanzang) traveled around Beijing, learned books and languages, sat down and asked for advice, and got through in a few days." It can be seen that Xuanzang learned the Indian language from foreigners. Probably in the Yijing era decades after Xuanzang's death, the learning conditions improved. As mentioned above, I ching and others have compiled some books on studying Sanskrit, which will be of great help to monks studying Sanskrit. For these situations, the Book of Changes is described in the Biography of Eminent Monks in the Western Regions of Datang. Xuanzang Biography said: "In the middle of Zhenguan, I studied Sanskrit in Zheng Xuan Branch of Daxing Shansi Temple." "Biography of Teacher's Whip" said: "Be good at forbidding spells and be idle in Sanskrit." "The Legend of Mahayana Lantern" said: "Sanskrit is quite idle." Daolian Biography said: "I went to Dharma in East India, lived there for three years and learned Sanskrit." Legend of Cleverness says: "Sanskrit is extremely idle." "Otsu Biography" said: "It took more than a month to reach the corpse, and the Buddha died in Zhou. I stopped for many years and learned Kunlun language, and Brahma learned it well. " Gu Zhen and four others "have been attached to the ship, and they are all dead. After studying for three years, Brahma and Han gradually became familiar. " Some of the monks mentioned in the Book of Changes studied Sanskrit in China, while others studied in Indonesia. In short, they knew Sanskrit before they came to India. What we want to inherit and carry forward today is not only in language research. In other fields, there is much work to be done. As we all know, Indian works, mainly Buddhist classics, which have been translated into the languages of various ethnic groups in China, are loaded with cars and tons of sweat. This includes Chinese, Tibetan, Mongolian and Manchu, as well as ancient Uyghur, Hotan, Yanqi, Qiuci and so on. Even Buddhist scriptures are not limited to Buddhist teachings. Many books are natural sciences in the name of Buddhist scriptures, such as astronomy and medicine. Indian people attach great importance to these Chinese translations of Buddhist scriptures and regard them as their extremely valuable cultural heritage. Unfortunately, it has long been extinct in our own country and only exists in China's translation. They planned to translate it from Chinese to Sanskrit decades ago. When I visited India in the early days of liberation, I saw the fruits of their efforts. When I arrived in India the year before last, I knew the work was still going on. It can be seen that the Indian people's attitude towards this work is serious and their spirit is admirable. We sincerely hope that they will make greater achievements. We in China should also make corresponding efforts to explore and study this cultural treasure house. Today, many countries in the world, such as academically developed European and American countries and Japan in the East, have made great achievements in this field. In contrast, for various reasons, we are obviously a little behind. If you don't catch up quickly, the gap will get bigger and bigger. When it comes to "seeking the wild for the sake of ceremony", you will regret it. In addition, there is a great deal of information about trade and cultural exchanges between China and South Asia, Southeast Asia, West Asia and Africa in the vast historical records of China. This is unmatched by any country in the world and is a treasure of mankind. Among them, information about India is particularly rich and precious. These materials also need us to collect, sort out, analyze and study. A very gratifying phenomenon is that in recent years, Indian scholars have paid more and more attention to this research, written some high-level papers and translated a lot of information about China. It is suggested that a complete history of Sino-Indian cultural relations should be written. They are willing to cooperate with Indian scholars and make joint efforts to promote the traditional friendship between the Chinese and Indian peoples and strengthen mutual understanding between the two peoples. I think we should also do our best to do research in this field.