The Legend of Korra OpeningWater. Earth. Fire. Air.
The world was torn by war for a hundred years.
The fire nation devastated the Earth Kingdom, Water Tribes, and Air Nomads, but everything changed when the Avatar returned.
With his friends, he was able to defeat the tyrannical Fire Lord and restore balance to the world.
Seventy years have passed since then.
The Earth Kingdom and Water Tribes have been rebuilt with help from the Avatar and the Fire Nation.
However, all is not well.
Since the Avatar's death, there have been anti-bending revolts in each of the nations, but particularly in Republic City, a new metropolis in the center of the Fire Nation.
No revolts have done much yet, but with time they could grow stronger and pose a threat to the peace and order established by the Avatar.
This newly recuperated world has come a long way in the past seventy years, but it needs a new Avatar to save it from spiraling downward into turmoil once again.