Long Night
The Long Night was a legendary winter of unending darkness that fell upon the world thousands of years ago during the Age of Heroes, when the Others descended from the uttermost north and nearly destroyed mankind. It is among the most ancient and dreaded events in the history of Westeros.
The Darkness
According to legend the Long Night lasted a generation, a winter that endured for years without end. In the cold and dark came the Others, pale cold creatures riding dead horses and raising the slain as wights. Crops failed, children starved, and across the world peoples told their own versions of the horror, from Westeros to the lands of Essos and beyond.
The War for the Dawn
The First Men and the children of the forest are said to have joined together to fight the Others in the War for the Dawn. By legend a hero, sometimes called the last hero, sought out the children for aid, and the threat was finally turned back. In the red faith of Essos, a savior named Azor Ahai wielded the burning sword Lightbringer against the darkness.
The Wall and the Watch
After the Long Night, Brandon the Builder is said to have raised the Wall of ice to guard the realms of men, and the Night's Watch was founded to hold it. The ancient fear is rekindled in A Song of Ice and Fire as winter returns and the Others stir once more, raising dread of a second Long Night.