Contrary to recent opinions, dragons did in fact exist in Medieval England and in Asia too. They were driven extinct by way of a deadly epidemic, a disease called Dragonis Killitis and over hunting by overzealous dragon hunters. In Asia, the dragons, of course, were wiped out by the commies in China back during the 60s and 70s. In Japan, they were eaten by Kaiju. Terrible losses all.
The reason why people think dragons never existed is because of a worldwide conspiracy orchestrated by the ever fiendish Illuminati, a secret society led by Kim Kardashian who, as you all should know, controls the world.
Yeah, that's right, I just blew the lid off that mofo! Open your eyes, sheeple!
Oh shit, I hear black helicopters. Gotta go!