When Wu Zetian became emperor, she never forgot that Li Zhi's last wish was to be buried back in Chang 'an, when Wu Zetian's capital was in Luoyang. So in order to choose a cemetery for Li, Wu Zetian recruited capable people, and Yuan Tiangang would do so, so Wu Zetian asked Yuan Tiangang to go to Chang 'an to choose a cemetery for Li Zhixuan.
Everyone knows that Yuan Tiangang knows Feng Shui, and he can do these things easily, so Yuan Tiangang went to Chang 'an, but he couldn't find a good place after searching for several months. At this time, he was staring blankly at the night sky. Unexpectedly, something magical happened. There is purple smoke above a mountain in the sky. He thought, this is purple gas from the east, which is a good sign, so he made a mark with copper money and reported it to Wu Zetian.
Later, Ganling was built in that place. After that, many people tried to go to Ganling for treasure, but there was no result. Grave robbers can't find the entrance to Ganling either. This story was spread by many ordinary people, so many people knew Yuan Tiangang's name and later stories.