For studying the history of Tatev Monastery – the spiritual and cultural center of Syunik, the primary source is the historical book by chronicler Stepanos Orbelyan (written in Noravank in 1297). The historian describes in detail the construction of the cathedral of Tatev Monastery and the placement of the relics of Saints Paul and Peter in the foundations of the twin columns of the temple, without mentioning the supposed disciple of Christ or Saint Thaddeus – Saint Eustathius (Eustace-State). The latter’s name is not attested in early literary and hagiographic sources either, but appears only from the 15th century onwards.
The main reason for concealing the names of Apostles Paul and Peter in Tatev and associating the monastery with the supposed Apostle Eustathius can be attributed to the church-political conditions of the time, when as a result of the pro-Latin position adopted by the Catholicosate throne in Cilicia, the Unitor movement expanded in Syunik with its center in Krna in Nakhichevan. From this perspective, it can be argued that this was the primary rationale for designating the spiritual and episcopal centre of Syunik as apostolic.
As for the toponym Tatev, it is mentioned multiple times in literary and epigraphic sources, the earliest of which is probably the family name Tatevians preserved in the “Nersesian” throne list, as well as Orbelian’s testimonies, manuscripts from the 13th-14th centuries, and contemporary monastery inscriptions, meaning the toponym Tatev is documented as the early medieval period and in subsequent centuries. Apart from the legend woven around the name of Saint Eustathius and its religious-political motives, the monastery’s main church today again bears the name of its holy apostles – Paul and Peter, while only the semi-ruined memorial pillar located outside the monastery wall on the northeastern side is associated with the name of St. Eustathius.