Test analysis: This question examines the related contents of Xuanzang's westward journey. During the period of Emperor Taizong, Xuanzang, a monk, went to Tianzhu to study and learn from the scriptures. After returning home, he dictated what he saw and heard in the journey to the west, and his disciples compiled a book. This is the famous "Datang Western Regions". It is of great research value to study the history and Buddhism of Central Asia, Indian Peninsula and China and Xinjiang, so the answer is A.