Tarkir

For many years, the five clans fought a war against the dragons for their own survival, hoping to gain some advantage in the struggle. Ultimately, the dragons were able to hunt down the khans and destroy them one by one. As each of the ancient humanoid khans fell, their clans fell with them in an known as the Khanfall. In place of the old humanoid clans rose the five dragon clans, named after their dragonlords: the elder dragons Dromoka, Ojutai, Silumgar, Kolaghan, and Atarka.