Packed inside those Welsh hills, that you think are hills? They’re volcanoes. Or they were once. Now they’re extinct, chuffed out. The whole rocky west British coast from Cornwall to Shetland is the husks and plugs of a line of dormant volcanoes, cooled treasure from inside Earth.
So what are dragons, really? Breathing fire, guarding treasure. Dragons are volcanoes. They tell you about water rivers, horizontal, but there are vertical rivers too. Fire rivers, that erupted up once through volcanoes, that cooled and got mined to rule worlds with. And who ever told you any of that?