The Tonatani Dragon are one of the Original 8 species of Laramidia and Appalachia before the Tannin. They were once one of the most powerful ancient empires of their time and tried to conquer the other kingdoms but they overextended themselves and collapsed their own kingdom instead.

The Tonatani were proud, righteous, and scholarly seeking to understand or make meaning in the world. They believe that they had figured out that the sun is the source and origin of all magic in the world; It is the energy that drives all life, it sets weather in motion, even the light of the moon is only a reflection of the sun's, and their species were the closest in the world to resemble the Sun's power, therefore they should naturally be in charge of all other Dragons.

The only thing they could not make sense of is how some dragons derive their magic from the Dark instead of the light...Everything else checked out:
Nature is Magic. Nature needs the Sun
The Moon is Magic. The Moon gets it's Light from the Sun
Crystals are Magic. Magic flows through them like Light.
So how can the absence of Light also have power if Light is Power?

Their conclusion was that the Magic that came from the dark must be a different source of power than theirs, and feared that it was something malicious. By their logic if the Power of Light creates and empowers Life and Motion in the world, then the Power of Darkness must be Death and Stagnation, a power that comes from the Void itself and seeks to swallow everything. This lead them to become especially hostile to a particular Dragon species who's powers were came from the Dark, and tried to propagate hostility against them but their radical position made more enemies instead of allies.
There are few groups of Tonatani are around today living in Appalachia and most of them want nothing to do with their old imperialist ways seeing it as a blight upon their history or a cautionary tale.

The Tonatani's power allows them to create Hard-Light constructs. They could simply be used as is but with them the Tonatani are also able to spell-craft using the same principal of how the crystal structure of Gemstones creates different results allowing spells to be cast through gemstones. Combining them on top of each other the Tonatani were able to create new and more complex spells that they could cast as long as they had a source of Light.