On Fairy Vearth, Eneru finds a group of alien-like creatures who have wings like the Skypieans.
The city that Enel found on the moon is called Birka, sharing the name of the Birka people.
After the 3 original inhabitant races ran out of resources in the moon, they travelled down to Earth and separated themselves.
The ancient Birka people formed an island nation on the clouds (called Birka), the ancient Shandorians formed a civilisation on Jaya, an island on the Blue Sea (called Shandora) and the Skypiea people formed an island nation on the clouds too (called Skypiea).
After the Shandora civilisation fell to the Twenty Kingdoms during the Void Century, a small tribe remained and was left with the legacy of their Shandorian ancestors, including the ruins of the golden city of Shandora, the poneglyphs and the golden belfry bell. This tribe became known as the Shandia.