X-Nais was a large planet in the Unknown Regions and second orbital in the Paryu system. Its atmosphere contained a large magnetic field as well as an overabundance of moisture, which caused numerous violent lightning storms. It was the homeworld of the Xians.
The planet was covered in one giant black cloud, except for in three to four (depending on the season) clear patches, where the moisture would escape into the vacuum of space, leaving a hole in the cloud. Xian astronomers placed observatories and labs under these areas, as they were the only sites on the planet where a being on the ground could see into space. Also, due to the profusion of water in the air, the atmospheric pressure pushed hard on the Xian bodies. The Force adapted the Xians to the pressure which caused them to become stronger with it and eventually they grew into a Force-sensitive species, taking dominance in the system. But that dominance was shattered when the Liberators invaded the system, in 18 BBY, and destroyed their dynasty. X-Nais, though, after the invasion of the Liberators became the center of commerce, industry, and goods in the system.