How has the story of Journey to the West evolved?

The story of Journey to the West has gone through a long process of evolution: the story of Tang Priest's pilgrimage to the West is deduced from Xuanzang's experience: in the first year of Zhenguan of Emperor Taizong, Xuanzang became a monk and illegally crossed the border, which lasted 17 years and passed through 100 countries. Go to Tianzhu (now India) alone to retrieve 657 Buddhist scriptures. Xuanzang told his disciples what he had seen and heard on his journey to the west, and he compiled it into "The Tale of the Western Regions of Datang". His disciples Huili and Yan Cong also wrote "Datang The biography of Master Sanzang", describing Xuanzang's deeds of learning Buddhism: in order to publicize Buddhism and celebrate Master's achievements, he couldn't help exaggerating and inserting some fairy tales, such as the lion king snatched a woman as his son, the western girl country failed to raise it, and Jia Shi Luo Guo "destroyed the evil Buddha". Since then, the story of learning from the scriptures has been widely circulated in the society, and the more it is spread, the more bizarre it is. In the notes of the Tang Dynasty, such as Historical Records and Legends of the Tang Dynasty, Buddhist stories have a strong magical color, and Buddhist stories in the Southern Song Dynasty began to link various myths with Buddhist stories. A walker appeared in the book: it turned out to be "the 84,000-copper-headed Monkey King in the Ziyun Cave of Huaguoshan" and became Untitled Scholar who escorted Sanzang: versatile and resourceful. This is the beginning that the central figure in the story of Buddhist scriptures has gradually changed from Xuanzang to the Monkey King. The image of the walker comes from the story of the white ape becoming immortal in China's ancient mystery novels, such as The Spring and Autumn Annals of Wu Yue, The Search for God and The Biography of the White Ape in Bujiang. Li Hongzhuo's "Ancient Classics" in which Huai Vortex is strange and martial, and his "God changes quickly" and rebellious character are particularly close to the legendary the Monkey King. The sand god in the book is the predecessor of the sand monk in Journey to the West, and Pig Bajie has not yet appeared. In the Yuan Dynasty, a more complete and vivid story of The Journey to the West appeared, and its main plot was very close to that of The Journey to the West. From the Song Dynasty to the Ming Dynasty, stories of learning from the scriptures often appeared on the stage of traditional Chinese opera. In the Southern Opera of the Song and Yuan Dynasties, there is The Monk on the Chen Guangrui River; During the Jin and Yuan Dynasties, there was Tang Sanzang; In Yuan Dynasty, Wu Changling had Tang Sanzang's Zaju of Journey to the West; At the end of Yuan Dynasty and the beginning of Ming Dynasty, there appeared the Zaju of Jitianshengda by Erlang God and the Zaju of The Journey to the West by Yang Jingxian. Before Wu Cheng'en wrote The Journey to the West, the story of learning from the scriptures had been widely circulated in the society in various forms. It is on the basis of these legends, commentaries and operas that Wu Cheng'en created this large-scale novel The Journey to the West.