Ammon News - Swiss author Erich von Daeniken, who helped popularize the idea that astronauts from outer space visited Earth ​to help lay the foundations for human civilization, has died aged 90.

Swiss media including national broadcaster SRF reported his death, and a note on his website said it occurred on Saturday, The AP news reported.

Von Daeniken rose to ‌prominence with ‌his 1968 book "Chariots of ‌the ⁠Gods?" ​which posited ‌that structures such as the pyramids of Ancient Egypt, Britain's Stonehenge and Peru's Nazca lines were too advanced for their time, and needed outside help.

"In my opinion, ancient structures were made ⁠by humans, not by the extraterrestrials, but it was ‌the extraterrestrials who guided them, ‍who them, ‍who gave them the knowledge how to ‍do it," von Daeniken says in a video on his YouTube channel.

His theories were controversial with historians, scientists and fellow ​writers. But they were popular, and his books, which included "The Gods were ⁠Astronauts", sold nearly 70 million copies worldwide, appearing in more than 30 languages, SRF said.

Von Daeniken argued that ancient religions, myths and art contained evidence that millennia ago, the ancestors of modern humans had made contact with advanced extraterrestrial beings who appeared godlike to them and enabled them to progress.

One ‌day, von Daeniken said, those beings would return.