Agartha

Agartha is a legendary kingdom said to be on the inner surface of the Earth. Though the story has many different versions, Agartha is usually said to be in Central Asia and led by a powerful figure sometimes called the King of the World, who secretly influences the surface. Later versions connect it to the belief in a Hollow Earth. The idea of Agartha has been a popular subject in esotericism, occultism, and the New Age since the late 19th century.