Oz is the imaginary land introduced by L. Frank Baum in his book The Wizard of Oz, and the setting for all of the "Oz" stories. Roughly rectangular in shape, it is divided along the diagonals into four countries: Munchkin Country in the East, Quadling Country in the South, Winkie Country in the West, and Gillikin Country in the North. These surround the Emerald City in the center. It is surrounded on all four sides by the Deadly Desert, which helps to protect it from discovery and invasion. It is further protected by a barrier of invisibility erected by Glinda. Oz is the largest country on the continent of Nonestica.