Will Wight
The Blackflame Empire
The Blackflame Empire was founded by dragons.
In Cradle, dragons are a race of sacred beasts that can...well, they're dragons. You know what they can do. Like all sacred beasts and Remnants, their intelligence is based largely on their age and advancement levels, so many of them have human-level intelligence or better.
A family of black dragons once conquered and ruled half a continent, which is a truly massive amount of territory in a world the size of Cradle. They held their empire against all rivals for centuries.
Until a mysterious disaster killed most of the dragons, crippling their ability to continue the bloodline. As you know, no one in a fantasy novel ever discovers the truth behind ancient disasters, so I'm sure it will remain a mystery forever.
With their rulers dead or dying, a clan of humans stumbled upon a method of harnessing the dragons' power. They abandoned their old Path, instead choosing to develop the same sacred arts used by the dragons.
The Blackflame Empire shrunk in size, the humans lacking the ability to control quite as much territory as the dragons could, though it was still home to over a billion people.*
This clan started calling their main branch the Blackflame family, for obvious reasons, and they stayed in control for almost five hundred years.
But human bodies were not well-suited to the power of dragons. Slowly, the family declined, until even those who lived in the heart of the empire thought of them more as symbols and legends than actual individuals.
More and more of the day-to-day workings of the Empire were left to the Blackflames' traditional servants, the Naru clan. They became the face of the Blackflame empire, with their loyal reputation and shining emerald wings, and the people grew to know and trust them.
Fifty years ago, they quietly ascended the throne.
The first Naru clan Empress has since moved into private seclusion, and her son now rules the Empire. As for the Blackflame family themselves, they died out decades ago, gradually eaten from the inside out by their own madra.
That's the story, anyway.
*(A truly ridiculous number of people live in Cradle. The main planet of Iteration 110 is quite a bit bigger than Earth.)