Cobble
As mentioned in Phantom Hourglass, the Cobble Kingdom was once inhabited by the ancient Cobble race. The remains of the Cobble Kingdom are found hidden beneath the water on the Isle of Ruins, and there is found the seventh dungeon, Mutoh's Temple. Some of the Cobble race are gifted with powers of premonition. These powers can increase even after death.
Civilization
The Cobble race ruled a large portion of the ocean in the world of Phantom Hourglass, until it fell mysteriously. They were expert architects, constructing the pyramids and tombs on the Isle of Ruin and the mechanical creation Eox, boss of Mutoh's Temple. Since Zauz is a descendant of the Cobble people, then they were likely excellent swordsmiths as well, as they possess the third Pure Metal Aquanine. Zauz also tells of how his ancestors would forge swords to defend the Ocean King against great evil.
The Cobble Kingdom allegedly had its own group of Sages, as the graves of nine of them are marked on the Isle of Dead. The King of the Cobble people was served by four Knights: Brant, Bremeur, Doylan, and Max.
Members of the Race
References
"Some of our people see far, with powers that grow when we pass from life." — Astrid (Phantom Hourglass)
"In seas ruled by the Ocean King, the cultured Cobble Kingdom soared above all. It was more glorious than any other city until it vanished from history!" — Explorer's Compass (Phantom Hourglass)
"You see, for generations, our ancestors lived to serve the Ocean King. They defended the Ocean King in an age when great evil lurked in the sea. My people forged our own weapons and fought in epic battles. You seek one of those great weapons. An artifact called the Phantom Sword." — Zauz (Phantom Hourglass)