Kenkori

This massive island is nearly a continent unto itself. It is a giant crater surrounded on all sides by massive cliffs. Giant eagles occupy the highest reaches of the cliff walls and they are served by a mysterious humanoid civilization.
Little is known of the savage humanoids who ride giant eagles and raid the main continents, and ships near the island. They are isolationists and are rarely seen except for raids into the continents for Moonsilver objects. It is known that they rarely take anything except items made of Moonsilver.