Narnia is the fictional world at the center of C.S. Lewis’s Chronicles of Narnia.
In the stories, Narnia is a land populated by humans, talking animals, dwarfs, giants, and other creatures. Its history begins with a creation scene described in The Magician’s Nephew, and its final chapter is told in The Last Battle. The world is ruled or protected at different times by figures including Aslan and human kings and queens.
Narnia is also the name of a country within the wider fictional universe, which includes places such as Archenland, Calormen, and the Lone Islands. Because “Narnia” can refer both to the central country and to the broader world in casual discussion, readers sometimes use the term more broadly than the geography strictly requires.
Middle-earth, Earthsea, and Prydain belong to other fantasy authors’ works, not Lewis’s Narnia series.