Korra was born in the Southern Water Tribe some time after the death of Avatar Aang. Not much is known about her early life. However, it can be assumed that at one point in her life Korra learned that she was the Avatar, and began to train in order to become a fully realized one. Having already mastered Waterbending, Earthbending, and Firebending, Korra only needs to learn and master the art of Airbending and gain full control over the Avatar State in order to become a fully-realized Avatar. About seventy years after the end of the War, Korra journeyed to Republic City seeking the tutelage of Tenzin, the son of Avatar Aang and Katara, as her Airbending master. During her travels, she discovered anti-bending unrest in the city. At some point, she gained an animal guide, a polar bear dog named Naga, and she will meet the sibling duo of Mako, a Firebender, and Bolin, an Earthbender, who all will also join her in the mission to rid the city of the Equalists.

by Avatar Wiki