Mythopoeia
Mythopoeia (, Ancient Greek: μυθοποιία, romanized: muthopoiía, lit. 'myth-making'), or mythopoesis, is a subgenre of speculative fiction, and a theme in modern literature and film, where an artificial or fictionalized mythology is created by a writer of prose, poetry, or other literary forms. The concept was widely popularised by J. R. R. Tolkien in the 1930s, although it long predated him.