According to The Encyclopedia of Science Fiction, “Lost Worlds” is a term that “covers lost races, lost cities, lost lands: all the enclaves of mystery in a rapidly shrinking world that featured so largely in the sf of the late 19th and early 20th centuries” (Clute and Nichols, 734-735). King Solomon’s Mines not only fits squarely into this definition, it is among the first—and is certainly the first popular—novels to use the “lost world” setting archetype.
Lost world fiction is connected to science fiction in that “These works are also distinguishable from earlier travellers’ tales [such as Swift’s Gulliver’s Travels] by their much greater ‘scientific’ content. The new sciences of geology, anthropology and, above all, archaeology had a considerable influence on Verne, Haggard, and their successors” (Clute and Nichols, 735). Haggard is credited with writing the first romantic adventures set in a lost world with his King Solomon’s Mines (1885), its sequel Allan Quatermain (1887), and She (1887). There were other, less famous lost world novels, as well as Sir Arthur Conan Doyle’s appropriately-titled The Lost World published in 1912. After Doyle, the lost world story fell out of favor, not to be rediscovered by the popular consciousness until the 1933 film King Kong. That same year, James Hilton published another lost world novel, Lost Horizon, which became a bestseller.
Since that time, the lost world story has once again faded from popular culture, occasionally to be resurrected but never again becoming long-running trend as it was in the late 19th century.