I don't know about never. I'm sure there was a time that we had to tame the dragons, way back when. It was just a long, long time before I was born. Oh, and wild dragons still exist! I don't think it's even possible to tame an adult fyulong. They mostly just leave us alone, though.

[He crouches to get a better look at Toothless, intrigued by the unfamiliar species.]

Never heard of Vikings, either...