The Story:
The Legend of ???.
Before Avatar Aang and his successor Korra, there were many more. Recorded history, however, has a trail that fades away whilst tracing back in time. Going backwards, before Avatars Roku, Kyoshi, Kuruk, Yangchen and the unnamed Magma Bender, the Avatar Spirit was within an ???bending host. This is hundreds of years before Aang triggered the Avatar State that would freeze him in a glacier for Sokka and Katara to find. Hundreds of years before Korra was even conceived.
I take you back before recorded history in the world of Avatar faded away to the memories of the dead lurking the Spirit World. Dragons have not been hunted to near extinction, and the Air Nomads did not yet fall victim to the wrathful genocide the Fire Nation would inflict hundreds of years later. The world is at peace, or perhaps I have spoken too soon? The previous Avatar has passed away, and the new host has been chosen. ???(the current Avatar) is the new host. At the time of ??? birth, to ??? year later to when our RP will take place, the world has been threatened. An unknown villain has lead a force assumed to be chi blockers to destroy benders. They have gone to villages and towns to "purify" the gene pools. They, however, leave the leaders alive and, instead, removing their ability to bend. If you've nostalgia to the Legend of Korra, think again. It is said that a powerful chi blocker has mastered an ancient, forgotten art and is out to not destroy only the Avatar Spirit, but the notabilities and councils of the four nations so that the ancient art could again be dominant. And they are training more to fuel this unjust cause.