I haven't written this up yet.
Note that Coba is the same world as Va. This does not stop sages listing them separately when they enumerate the Fifty Worlds. Coba is the old name for the world, and is used for the part of the world which used to be populous but is now virtually deserted. Va is the new name for the world, and is used for the part of the world around the city of Megalopolis. It is practically impossible to travel between Coba and Va, so for most practical purposes they are indeed separate worlds.
Coba has two moons. I'll add more about them later.
The name Coba derives from the colour of the sky, which is cobalt blue.