The fictional country created at the beginning of C.S. Lewis’s Narnia chronology is Narnia.
In The Magician’s Nephew, the sixth book by publication order, the character Aslan sings Narnia into existence. The new land contains forests, rivers, animals, and other living beings, and it becomes the central setting for the rest of the series. This creation scene occurs long before the events of The Lion, the Witch and the Wardrobe.
Narnia can refer both to the country itself and, in broader usage, to the fantasy world or universe containing several lands. That wider world also includes places such as Archenland, Calormen, and the Wood between the Worlds. Charn, by contrast, is a separate, dying world visited earlier in The Magician’s Nephew.
The name has become so strongly associated with Lewis that “Narnia” is often used informally to mean the entire fictional setting, even when a particular scene occurs elsewhere.