They were as uncommon abroad as they were in the Empire, and every country prized them alongside their dragon knights as being one of the few forces capable of aerial combat.
Thinking about it for any length of time was enough to see why. From a tabletop perspective, taking to the air was up there with long-range teleportation in its ability to nip a campaign in the bud. Whether the heroes were to sneak into an enemy base or get past a blockade, the ability to fly nullified all the awful traps the GM stayed up at night designing with a devilish grin.
It was downright unethical. The day I designed a booby-trapped hallway only to hear, “Er, I float five centimeters off the ground and go through, and I’m gonna tie a rope up high on the other side for everyone to climb on,” would never leave me...