The zhian'tara was a Trill ceremony in which the present host can meet with past hosts. The personalities of past hosts are placed in the bodies of the current host's closest friends. (DS9 episode: "Facets"; DS9 - The Lives of Dax short story: "Sins of the Mother") In the year 2376, during the USS Defiant's voyage in the Gamma Quadrant, Ezri Dax thought about returning to Trill when the mission was over to undergo the zhian'tara. (DS9 - Mission Gamma novel: This Gray Spirit) Jarem Kaz had not undertaken the zhian'tara as of 2378. (VOY novel: Old Wounds)