The Desolations

Desolations are cataclysmic events in the history of Roshar (i.e., cyclical wars) when the forces of Odium - including the mysterious Voidbringers - supposedly attack Roshar in order to exile humankind to Damnation. Each time the forces of Odium were defeated they would retreat to Damnation but they would always return, beginning the conflict anew.

Humanity was aided in their fight each time by the appearance of the Heralds and their orders of Knights Radiant. Each Desolation the Heralds would build up human society and industry to aid in their battle against the Voidbringers. Until the Final Desolation (Aharietiam), when the Heralds made their final stand against the Voidbringers, sacrificing their lives to bring peace to Roshar. 

Desolations were destruction made manifest. Each one was so profoundly devastating that humankind was left broken; populations ruined, society crippled, scholars dead. Humankind was forced to spend generations rebuilding after each one. Songs tell of how the losses compounded upon one another, causing humankind to to slide farther each time, until the Heralds left a people with swords and Fabrials and returned to find them wielding sticks and stone axes.

Conflict Type

War

"In the aftermath of each one, mankind was broken. Great cities in ashes, industry smashed. Each time, knowledge and growth were reduced to an almost prehistoric state - it took centuries of rebuilding to restore civilization to what it had been before." - Jasnah Kholin