Are dragons real? - I was asked.
I had to think a bit.
The answer was not as straightforward as just No; because for many hundreds of years dragons were as real as anything else that one had not actually seen for oneself.
If we use high quality historical resources, such as the Anglo Saxon Chronicle, we find:
A.D. 793. This year came dreadful fore-warnings over the land of the Northumbrians, terrifying the people most woefully: these were immense sheets of light rushing through the air, and whirlwinds, and fiery dragons flying across the firmament. These tremendous tokens were soon followed by a great famine: and not long after, on the sixth day before the ides of January in the same year, the harrowing inroads of heathen men made lamentable havoc in the church of God in Holy-island, by rapine and slaughter. Siga died on the eighth day before the calends of March.
Nowadays we believe (I think) everything written here was real, except for the dragons.
Because we know (we think we know) that dragons cannot exist, therefore the reference to dragons must be mistaken, or metaphorical - or something...
History is no guide to what is real, not least because history changes - open-endedly.
History is partial, misinterpreted, distorted, subject to addition, subtraction and radical re-emphasis.
Nor is the evidence of our eyes a reliable guide to reality; because we know for sure that sometimes we dream (maybe we are dreaming now?) and have visions (is this a vision or is this real?) and may be suffering hallucinations, and our beliefs may be deluded.
What is real is perhaps that which is even now actually in some place where (in principle) it could be checked and known.
For dragons to be real, they must exist now; and I must actually have experienced them - but not with my fallible senses, nor recorded in my fallible memory - rather with revelation (divine communication) to my eternal soul or spirit - that 'me' which is independent of circumstances and cannot be deceived and can know that it is not being deceived.
All of which is setting the bar pretty high for reality; yet we still could not convince a skeptical other...
So dragons are not real, and neither is a lot of other stuff from history which we think we know is real; OR dragons were as real as the Vikings but we happen to have no archaeological evidence of them; or MAYBE they were and are real, and remain accessible, but I just don't know about it...