The Legend of Korra, Season 2

Tonraq:
You don't even know if what Unalaq says is true.

Unalaq:
You want proof? Look to the sky. Where I'm from, the spirits are at peace, and they light up the dark.

Korra:
The Northern lights.

Unalaq:
Yes. There used to be lights in the South as well. But during the Hundred Year War, the South was thrown out of balance, and the lights disappeared. When the war ended, the North helped to rebuild physically as a nation. But we have not rebuilt spiritually. Now the spirits no longer dance in your skies. Instead, they rampage in the Everstorm.