It was the place where the final ritual was conducted of the Kolinahr where a Kolinahri acolyte purged themselves of their emotions. The Plateau was a desolate region that was just outside the Kolinahru Monastery. The ceremony itself followed a ten day period of leave taking where the acolyte was allowed to leave the monastery and meet with as many of his lifetime friends as were possibly in order to bring closure to their memories. Afte which, the acolyte traveled alone into the desert where they carried only the robe on his back and a waterskin as they entered a deep meditative trance. In this state, they began casting out all the remaining emotions they had into the surrounding sands.
The ritual was known to take days or even weeks and only ended when the High Master determined that the cleansing of the new adept's mind was complete or if they were in danger. The High Master also used their telepathy to monitor the adept's progress of the ceremony. However, this ceremony was not always a successful one as an adept could go through several such ceremonies in their lifetime without ever fully breaking free of the bonds of their emotions. (Last Unicorn RPG module: The Way of Kolinahr: The Vulcans)