https://rationalwiki.org/wiki/Ancient_astronauts
"However, the fifties and sixties were more dominated by European works. The Italian Peter Kolosimo wrote several books as early as 1957, but his Timeless Earth (1964) became an international best seller and was translated into several languages. French-language authors included Henri Lhote who proposed that prehistoric Saharan rock art depicted close encounters, Bergier and Pauwels' Morning of the Magicians (1960), Robert Charroux's One Hundred Thousand Years of Man's Unknown History (1963) and Misraki's Flying Saucers Through The Ages. A few British authors also published before Von Däniken, such as Brinsley Le Poer Trench, John Michell and W. Raymond Drake who wrote Gods or Spacemen? in 1964.
"Although Von Däniken claims he was formulating his ancient astronaut ideas throughout his school days, it is clear that many others had already published their books on the subject, long before he became notable with Chariots of the Gods? in 1968."