He was the younger brother of Gubazes II, who was assassinated by Byzantine generals in autumn 555.
At the time, Tzath resided at the Byzantine capital, Constantinople, and the Lazi sent a delegation to the Byzantine emperor Justinian I (r. 527–565) to request both justice for their murdered king and the confirmation of Tzath as their new king (the Lazic rulers, as client kings, had to have their accession confirmed by the emperor, who awarded them with their regalia).
Tzath arrived in Lazica in spring 556, accompanied by the magister militum Soterichus, and was received in an elaborately staged welcome ceremony.
[1][2][3] Tzath II is the last known ruler of the dynasty of the kings of Lazica.
After the Byzantine–Iranian treaty of 561/562, that ended the Lazic War, Lazica gradually disappears from the sources.