Originally, the Shinobi World had possessed its own cultivation system.
Whether human or beast, everyone cultivated natural energy to achieve longevity.
If supernatural power could not grant longevity, how could it even count as supernatural power?
Besides, it was not as though long-lived creatures did not exist.
Nor was natural energy some nonrenewable resource with a fixed total supply.
As long as cultivators did not absorb it at a rate exceeding the entire world's limit,
Natural energy could actually grow more abundant the more it was used.
That was because more people cultivating would drive the world's development and evolution.
The better the world developed, the higher its limit would rise, naturally increasing both the quantity and quality of the natural energy contained within it.
In turn, this would nourish its inhabitants and raise the upper limit of cultivators' strength.
The two complemented one another, and neither could do without the other.
However, because the native cultivation system was somewhat difficult to practice, it had been phased out extremely quickly after the two Ōtsutsuki brothers introduced a cultivation system called chakra.
But chakra was a foreign cultivation system that did not cultivate natural energy, so Xian could not obtain energy from it to restore its essence.
As for that little bit of senjutsu chakra, it was hardly worth mentioning. Who had ever seen a forest fire raging across the mountains extinguished with a few flecks of spit?
Without cultivators, the existing natural energy alone could not restore Xian's essence.
Of course, being unable to recover would not make its condition any worse.
The problem was that more and more hidden realms and small planes were appearing in the Shinobi World, such as the Pure Land and countless summoning realms.
The Pure Land itself severely obstructed the world's normal development.
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