The density of spiritual energy in the mortal realm was high, especially so in Jing Nation.
One of the most important factors was Gu Lan burying the Nine Heavens Earth Essence in Tianqiong Mountain, continuously stimulating it with formations. As a result, not only did the Nine Heavens Earth Essence grow larger in volume, but it could also emit astonishing spiritual energy at a fast rate.
After a simple calculation, Gu Lan estimated that it would only take a hundred years for the spiritual energy density in the mortal realm to rival some of the sparse areas in the Immortal Realm. This speed was already astonishing.
Even the strong from the Immortal Realm and Demon Realm who came down were amazed by the changes in the mortal realm every day. However, when they learned that it was Gu Lan's doing, they weren't so surprised. Over the years, they had seen too many incredible things from Gu Lan and had gradually become accustomed to it.