The lost world is a subgenre of the fantasy or science fiction genres that involves the discovery of an unknown Earth civilization. It began as a subgenre of the late-Victorian adventure romance and remains popular into the 21st century. The genre arose during an era when Westerners were discovering the remnants of lost civilizations around the world, such as the tombs of Egypt's Valley of the Kings, the semi-mythical stronghold of Troy, the jungle-shrouded pyramids of the Maya, and the cities and palaces of the empire of Assyria. Thus, real stories of archaeological finds by imperial adventurers succeeded in capturing the public's imagination. Between 1871 and the First World War, the number of published lost world narratives, set in every continent, increased significantly. The genre has similar themes to "mythical kingdoms", such as Atlantis and El Dorado. History King Solomon's Mines (1885) by H. Rider Haggard is sometimes considered the first lost world narrative. Haggard's novel shaped the form and influenced later lost world narratives, including Rudyard Kipling's The Man Who Would Be King (1888), Arthur Conan Doyle's The Lost World (1912), Edgar Rice Burroughs' The Land That Time Forgot (1918), A. Merritt's The Moon Pool (1918), and H. P. Lovecraft's At the Mountains of Madness (1931). Earlier works, such as Edward Bulwer-Lytton's Vril: The Power of the Coming Race (1871) and Samuel Butler's Erewhon (1872) use a similar plot as a vehicle for Swiftian social satire rather than romantic adventure. Other early examples are Simon Tyssot de Patot's Voyages et Aventures de Jacques Massé (1710), which includes a prehistoric fauna and flora, and Robert Paltock's The Life and Adventures of Peter Wilkins (1751), an 18th-century imaginary voyage inspired by both Defoe and Swift, where a man named Peter Wilkins discovers a race of winged people on an isolated island surrounded by high cliffs as in Burroughs's Caspak. The 1820 Hollow Earth novel Symzonia has also been cited as the first of the lost world form, and Jules Verne's Journey to the Center of the Earth (1864) and The Village in the Treetops (1901) popularized the theme of surviving pockets of prehistoric species. J.-H. Rosny aîné would later publish The Amazing Journey of Hareton Ironcastle (1922), a novel where an expedition in the heart of Africa discovers a mysterious area with an ecosystem from another world, with alien flora and fauna. Edgar Allan Poe's The Narrative of Arthur Gordon Pym