who are all the avatars in 阿凡达 the legend of aang?

Here's what I know. The airbending one was Yang Chen, then there was a waterbender named Korak(something like that) then the earthbending one, Kyoshi, and then Roku. Then there's Aang. That is the order from oldest to newest that has been mentioned on the show.

Aang is the newest incarnation of the spirit of the planet, which has been continually reincarnated since before memorable history. The passage of reincarnation moves from the population of the Air nation to the Water, Earth and 火, 消防 nations in order. The most 最近的 incarnations were 阿凡达 Roku (fire), 阿凡达 Kyoshi (earth), 阿凡达 Kuruk (water) and 阿凡达 Yangchen (air).

(quoted from 阿凡达 wiki)