Kapitel 95: AvC : Dragon Realm

Rein said that they were hierarchy in this world. 

Like a pyramid chain, they were races who were at the bottom and races who were at the top. 

Those who had low strength and timid races like the rabbit clan and fox clan were at the bottom. In the middle were the strong ones and who had strong attack power like the snake clan and tiger clan. At the top, there was only one race that dominated all the races, it was the dragon clan.

But the dragon clan was said to be on the path of extinction due to the lack of offspring. It was rumored that their god abandoned them because of their despotic nature and terrorizing other clans centuries ago. Their existence became rare and no one had seen one in hundreds of decades.

They probably gone instinct or they've been living in another hidden land like the Avian race.