Sun Simiao, the Medicine King, was a real person from Huayuan in Jingzhao (now Yao County, Shaanxi Province) in the Tang Dynasty. He was intelligent and quick-witted since childhood and could recite a thousand characters every day. When he grew up, he was proficient in the doctrines of Laozi, Zhuangzi and the Hundred Schools of Thought. During the reign of Emperor Xuandi of the Northern Zhou Dynasty, due to political unrest, he lived in seclusion on Mount Taibai to study Taoism and seek the immortal arts that transcended the mortal world. He had a profound understanding of astronomy and the art of observing celestial phenomena and divination. He was especially proficient in treating diseases and using medicine. Moreover, he was kind-hearted and always put accumulating hidden virtues first in his conduct and dealing with things.

Once, by chance, when Master Sun went out, he saw on the road that someone was about to beat a small green snake to death. The snake had already been injured and was bleeding. Master Sun quickly pleaded with the passer-by to stop. Since he didn't bring any silver with him when he went out, he took off his clothes to redeem the small snake, applied medicine to it, and then released it into the grass.

A month later, when Master Sun went out again, he met a young man in white clothes with many attendants. The young man dismounted from his horse and came forward to bow and thank Master Sun, saying, "My younger brother was saved by you, sir. My parents would like to meet you."

Master Sun had saved so many people that he didn't take it to heart. Hearing these words, he didn't pay much attention to it and declined the invitation. The young man earnestly bowed and thanked him again and invited him once more. Master Sun had no choice but to go with him. The horse galloped as if flying, and soon they arrived at a manor. The flowers and trees there were full of the peaceful and bright charm of spring. The entrance was magnificent, and it looked like the residence of a prince or a noble at first glance.

The young man invited Master Sun to enter. Inside, a middle-aged man wearing a crimson robe saw Master Sun and came up to greet him cheerfully, thanking him and saying, "I've missed you so much, sir. So I sent my child to meet you. Not long ago, my little son accidentally went out and was unexpectedly hurt by some fools. Thanks to you taking off your clothes to redeem him, his life was saved. Our whole family is grateful for your life-saving kindness. It's really an honor to meet you today, sir!"

Immediately after that, Master Sun was invited into the inner hall. It seemed to be the inner chambers of a palace. A middle-aged woman came out with a child in black clothes and repeatedly bowed and thanked him, saying, "My child is rather dull-witted and was injured by others. Thanks to your rescue, sir, he escaped death."

Only then did Master Sun remember that he had once saved a small green snake. He couldn't help but be full of doubts: Where was this place? He also saw that there were many servants around, and they called the middle-aged man "Your Majesty" and the middle-aged woman "Your Concubine". He was very surprised and quietly asked the people beside him, "Where is this place?"

The answer was, "This is the Water Palace of Jingyang."

It turned out that the "Your Majesty" was the Dragon King of Jingyang. That day, he specially invited guests and subordinates, arranged a banquet and played music to entertain Master Sun.

After that, Master Sun was about to take his leave. The Dragon King asked Master Sun what kind of thank-you gift he wanted. Master Sun replied, "I live in the mountains to practice Taoism and cultivate my spirit. I don't seek other things."

The Dragon King thought that Master Sun was just being too modest, so he presented light silk and precious pearls. But Master Sun firmly declined and refused to accept them. The Dragon King was in a dilemma and said, "Sir, you are truly a person with profound Taoist cultivation. But how can I repay you?" After thinking for a long time, the Dragon King ordered his son to fetch thirty medical prescriptions secretly stored in the Dragon Palace and give them to Master Sun, saying, "You are a true man of virtue. With these, you can help the world and save people."

Then he prepared horses and personally sent Master Sun back to his residence. Master Sun tried using the thirty medical prescriptions to treat diseases, and the effects were truly miraculous. Later, when he compiled the "Prescriptions Worth a Thousand Gold", he also included the prescriptions from the Dragon Palace in the book. The "Prescriptions Worth a Thousand Gold" is a famous medical masterpiece through the ages and has benefited countless people in the world. Master Sun not only saved countless lives but also achieved success in his cultivation of Taoism. Therefore, he was honored as the "Medicine King" by the common people in later generations.