In C.S. Lewis’s fantasy novel The Magician’s Nephew, the world created by Aslan’s song is Narnia.
The novel presents Narnia’s creation as part of its origin story. Digory Kirke and Polly Plummer arrive in darkness after using magical rings and encounter Aslan, the great lion. His singing brings light, stars, plants, animals, and eventually the first king and queen of the new land into existence.
The book was published later than the other main Narnia novels, but its events occur first in the internal chronology. It also explains the origin of the wardrobe’s wood and the arrival of the evil Jadis, who later becomes the White Witch.
Charn is the dying world from which Jadis comes, while Archenland and Calormen are countries within or near Narnia’s wider setting. None of those names refers to the newly created world itself.