While Xuanzang was a real historical figure who traveled to India in the 7th century and brought back Buddhist scriptures, Si Yu Ki is a fictional novel written by Wu Cheng'en in the 16th century.
Here's a breakdown:
* Xuanzang: A real Tang Dynasty monk who embarked on a pilgrimage to India in search of Buddhist scriptures. He spent 17 years there and returned with a vast collection of texts. His life and journey inspired the story of Si Yu Ki.
* Si Yu Ki: A novel that tells the story of a Buddhist monk, Tang Sanzang (based on Xuanzang), who travels to the West (India) to retrieve Buddhist scriptures. He is accompanied by three disciples: Sun Wukong (the Monkey King), Zhu Bajie (the Pig), and Sha Wujing (the Water Demon). The story is filled with mythical creatures, fantastical adventures, and Buddhist teachings.
Therefore, Si Yu Ki is not a factual account of Xuanzang's journey but a fictionalized retelling based on his life and adventures. It is a popular Chinese novel that has been adapted into numerous films, TV series, and video games.