Dragon

Dragons are majestic, powerful winged creatures that live on Argonessen, and they form one of the oldest civilisations on Eberron. They were one of the first creatures to appear on Eberron, alongside the Couatl, and were the first mortal creatures. They resemble gigantic, winged reptiles. True dragons are generally four-legged with two wings, and a powerful tail. Their hands and feet bear razor sharp talons, and a muzzle full of teeth fitting of their role as apex predators. They grow more powerful (and larger) as they age, and they are perhaps most well known for their breath weapons. Each dragon is capable of unleashing a devastating breath attack, but the exact nature of this weapon depends on the individual dragon (though there are some helpful groupings based on colour.)
When the fiends rose from Khyber and ushered in the Age of Demons, the dragons (and the couatl) were scattered and subjugated. Eventually, the couatl and the dragons went to war with the demons. Two of their greatest prophets, a blue dragon named Ourelonastrix and a powerful couatl named Hezcalipa, discovered the Draconic Prophecy and found within it a path to the future, a future without the overlords. For years the conflict raged on, with battles being fought between the demons and the dragons all over the world, eventually ending in the sacrifice of the couatl to form the Silver Flame. With the demons bound and the couatl gone, the dragons were the most powerful creatures left on Eberron.
The dragons settled Argonessen in the aftermath of this conflict, and from there began to keep an eye on the world and branch out into it. It wasn't long before they realised that their interference in world events were strengthening the Daughter of Khyber , and so they withdrew to their continent and intervene only rarely. One such instance was against the giants of Xen'drik. The dragons taught the giants magic, which they used in their war with the Quori, culminating in the destruction of one of Eberron's moons. The dragons didn't intervene then, but when the giants turned their eldritch machines against the elves that were revolting, threatening Eberron itself, the dragons stepped in and annihilated them.
Not only did the dragons kill most of the giants, they tore down their cities and cursed the land they had settled so that it could never happen again. The full force of Argonessen hasn't been seen in the world since their destruction of the giants. More isolated conflicts with Aerenel occur periodically, but the Undying Court is powerful enough to repel the dragons, and limited enough that they cannot push back into Argonessen.
When the Line of Vol succeeded in creating a half-dragon with a dragonmark, the dragons worked together with the other elven lines and eradicated them completely. Outside of these interactions with Aerenel, the dragons have remained relatively uninvolved in the goings on outside of their continent. There are rare instances of rogue dragons interfering, such as the rampage of Sarmondelaryx or Vvaraak teaching the Gatekeepers how to use magic and interpret prophecy.

Lifespan

Thousands of years