The Long Night
From A Wiki of Ice and Fire
The Long Night is the name given to a period in history where a terrible darkness fell across Westeros and the east. It occurred during the Age of Heroes approximately eight thousand years before the War of Conquest, in the midst of a great winter that lasted for years. The Long Night lasted a generation and laid waste through famine and terror.
War for the Dawn
According to legends, in the midst of this darkness a race of apparent demons, called the Others, emerged from the uttermost north, the polar regions of the Lands of Always Winter. They wielded razor-thin swords of ice and raised wights to fight the living. The children of the forest and their allies, the First Men, fought valiantly against them, but were driven southwards by their advance.
The Others were eventually checked when it was discovered that weapons made of dragonglass could kill them. The first members of the Night's Watch drove the Others back in the Battle for the Dawn. Other legends state a great hero, who in the eastern tradition is known as Azor Ahai, led the war against the Others wielding his sword of fire, Lightbringer, driving the Others back. In the Westerosi tradition, he may be known as the last hero.
Steps were taken to ensure that the people would never be caught offguard by an invasion from the North again. Bran the Builder supposedly raised the Wall, an imposing structure of solid ice and magic, stretching one hundred leagues from the Gorge in the west to the Shivering Sea in the east, cutting off the Lands of Always Winter from the remainder of Westeros. The Night's Watch guarded the Wall and protected the people from the threat that lay to the north.
|“||The oldest histories we have were written after the Andals came to Westeros. The First Men only left us runes on rocks, so everything we know about the Age of Heroes and the Dawn Age and the Long Night comes from accounts set down by septons thousands of years later. There are archmaesters at the Citadel who question all of it.||”|