Introduction to the apprenticeship gate: There is a triangular stone cave entrance when entering the Grand Canyon. Back then, Mulan wanted to become Taoist Priest Li Shuntian as her apprentice. Seeing that Mulan was a little upset, the Taoist priest used his fairy energy to blow a huge stone on Tianmen Pavilion. A cave door was built here that could only allow people to bend in and out slowly, and Mulan was required to enter and exit 800 times within half an hour before accepting her as her disciple. When Mulan went in and out of the cave, she would hit her head and bleed if she walked in a hurry, and she was afraid of running out of time if she walked slowly. Mulan, who was blessed with good spiritual skills, realized the good intentions of her master, calmly walked in a hurry, and finally obeyed her master's instructions. The request was fulfilled, and Mulan followed her master to cultivate her character, practice martial arts, and finally obtain the true teaching.