Boxen was the imaginary country created by C.S. Lewis and his brother Warren during childhood.
The Lewis brothers developed elaborate private stories and illustrations about talking animals and invented societies. Their early imaginative world was first called Animal-Land and later combined with another setting to become Boxen. The material included maps, histories, politics, and narratives rather than being a simple collection of names.
Boxen is important because it shows how early Lewis practiced world-building long before he wrote the Chronicles of Narnia. His childhood interest in invented countries, animals, and mythology later fed into his published fiction, although Boxen itself is not the setting of the Narnia books.
Readers often answer Narnia because it is Lewis’s famous fantasy world. Narnia was created for his published children’s novels decades later; Boxen belongs to the private imaginative work of Lewis and Warren’s youth.