Toril consists of several large continents, including Faerûn, the western part of a continent that was roughly modeled after the Eurasian continent on Earth.: Faerûn was first detailed in the original Forgotten Realms Campaign Set, published in 1987 by TSR. The other continents include Kara-Tur, Zakhara, Maztica, and other yet unspecified landmasses. Kara-Tur, roughly corresponding to ancient East Asia, was later the focus of its own source book , published in 1988.: There is also a vast subterranean world called the Underdark beneath the surface.: