I'm interesting in an avatar RP, but I'm having a hard time understanding the story. Who is Lian Shu, and what time period does this take place? 

I ask because the story says the avatar cycle is over, and then goes back in time to before Aang, and then to the point where Aang was in ice, then something about Chi Blockers and Equalists which is the Legend of Korra, and then Lian Shu shows up and is like "This is my story now." 

I'm confused.