Who prepared the elixir of immortality for Genghis Khan?

In the year of the fall of Otrar, the Taoist monk Chang-chun, enlightened and engaged in many mysteries, received an invitation - even a request - from a man whose name terrified half the world.

«I wear the same clothes and eat the same food as the shepherds and herders. I take care of the people as if they were a newborn child and I take care of the soldiers as if they were my brothers ... Show me your mercy and tell me of the means to preserve life». Genghis Khan

To show that mercy and fulfill the request, the monk would have to travel a long way from North China to Afghanistan and India, where Genghis Khan was situated at that time. But the enlightened Taoist took a different path. How did this come about, and did he share the miracle cure? This is a journey to trace the hidden paths of the immortal and learn the secret of eternal life.