The vimanas were the flying devices that were invented by ancien Indian civiliazationn, and descibed in detail in ancient Indian texts. Some have said they were disc shaped and resembled UFOs.
References:
Childress, David, Vimanas - Aircraft of Ancient India and Atlantis, Kempton, Illinois: Adventures Unlimited Press, 1991, 2004;
Ramachandra Dikshitar, V. R. War in Ancient India, Madras, India and London, UK : Macmillan, 1944
Sutherland, Mary Vimanas- Ancient Flying Saucers of Atlantis and Lemuria, 2010, PDF, 20 pages;
Wikipedia page on Vimanas (Skeptical viewpoint): https://en.wikipedia.org/wiki/Vimana