Shortly after the Dark One Tainted saidin, an Aes Sedai with the Foretelling had a vision that a pool of untainted saidin would be needed. This Aes Sedai gathered a group of both male and female channelers to accomplish this. The only males at the time who were insane were the survivors of Lews Therins' Hundred Companions who went mad on the spot. For the rest of the male Aes Sedai, they detected a difference, but went insane and rotted away gradually. Anyway, this group sacrificed their lives to pull as much saidin through a filter of saidar to purify it, and then they worked together to accomplish the even more difficult task to fix this pool into a single place (there is a quote earlier in the series that it would take every Sister in the Tower to fill one spoon with a physical manifestation of The One Power, just to give an idea of the immensity of the energy necessary).

Here is a reference from the Seven Spokes page: "In the early days of the Breaking one-hundred Aes Sedai, both male and female, create a pool of untainted saidin called the Eye of the World. The effort required to ensure the pureness of the pool kills all of the Aes Sedai involved. Set to guard the pool is the Green Man, a Nym." The Eye Of The World Hardcover page 625 / The Big White Book page 248

Rand essentially figured out how the Aes Sedai in that group separated the taint from saidin to purify it. Which is sort of interesting if you remember RJ's concept of the cycle of time and how communication works - if Lews Therin had agreed to Latra Posaes' plan at a different moment, and saved the Access Keys and THEN went to Seal the Dark One, this group of Aes Sedai could have used the Choedan Kal to remove the taint from saidin.



Yes - I think it exists in a vacuole of space/time that is attuned to T'A'R and t'a'veren. I think it moves by not being bound by physical laws of space/time. No, I don't think it exists partially in t'a'r. I think it was made by the AS in that Circle so didn't exist before.



Personally, I think there was nothing magical about chora trees besides the fact that they were cared for very carefully so that they grew either larger and/or into more beautiful shapes than trees normally did. I think, once again a nod to the cycle of time on a massive scale, that all that is needed is for someone to carefully breed a plant so that it once again could flourish. But this type of activity needs peace and prosperity, so it will probably occur after Tarmon Gaidon.