The saddest of songs...

The dragons vacated the planet known as Earth millennia ago. They came in peace, but in every land they visited, the humans saw the dragons with their fire breath, and whip tails and enormous wings as the enemy. Something to be destroyed to ensure survival. The dragons spent a thousand years telling mankind of a different way, without pain and cold and darkness. But the humans didn't hear. So the dragons left. Boarding their shining oblong ships they went back to the stars, never to return. If they were to meet man again, man you'll have to come to them.