From Tar Valon Library
Author: Kyria d'Oreyn
Devisor: Toma dur Ahmid
Dating: AB for After the Breaking
Due to the commotion that still shook the earth after the Breaking of the World, the starting point of this calendar was only a guess. The Toman Calendar was not initiated until approximately two hundred years after the death of the last male Aes Sedai, which is the official end of the Breaking.
With the end of the Trolloc Wars and the destruction of so many records, however, the years under this system could not be exactly dated anymore and a new calendar was needed. To replace it, the Gazaran Calendar was created.
(Reference: The World of Robert Jordan's "The Wheel of Time")