At the heart of Kun City, there was a facility near the defunct teleportation array. It was a massive stone arch inscribed with grade 7 refinement. It was made of kukan stone. Quite literally, space stone.
It was from a massive mountain that had actually come from a Ruin. When the barrier broke down entirely, the mountain settled on the layer and all found the wonderful stone.
It had no name or reference even the Radiant Tiers could give so it was named for its effect.
It allowed cultivators to study the Laws of Space quite effectively and production masters learned by leaps and bounds by experimenting with it.
When the Corruption spread, it was one of the few materials left unaffected. Refiners at the peak of grade 7 found they could create spatial gateways Immortals could still use to travel quickly but at extreme expense.
