Eien no Kiken Shouto

The Eternal Danger Islands was the first island formed in Ningen-do.

Creation
The Eternal Danger Islands were formed at the dawn of creation, by some of the water kami who wished for a place which embodied their nature most completely, which would be infused with their healing powers. Eventually they and the Earth kami together brought forth a massive piece of land from the very ocean itself, a process which took place over so long a time. It was imbued Within a few years, lush vegetation sprouted up everywhere, and all manner of wildlife thrived in profusion.

Naga
The first race which set foot on the island was the Naga, and quickly learned of its healing powers. Countless Naga traveled to the island and established a permanent settlement.