Hua Hu Jing is an ancient Taoist scripture that was written in China in the fourth century. The book stated that Lao Tzu, after having finished the Tao Te Ching and discovering Tao (the way with nature), left China for India, where he taught a disciple named Sakyamuni. This disciple founded a religion called Buddhism, which preached kindness to all.
Its story was challenged by Buddhists and deemed as slander. For centuries, debates between the two religions were held without result until Kubilai's reign when the Taoists were finally defeated and the Mongol emperor decreed that all copies of Hua Hu Jing were to be banned and burnt.
Hanson Chan, author of the novels Hua Hu I—The Forbidden Scripture & Hua Hu II—Thunder Spell, used this historical incident as background and wrote the story of a Taoist girl who at the last request of her Sifu, must save the sole surviving copy.