The centurion Caius Sacidius Barbarus, bearer of a rare gentilice attested in particular in the region of Mount Hermon, in Syria, has carved out a place of choice in the historiography of Mithraic studies for being potentially the author of the oldest Latin dedication to the god.
The legion XV Apollinaris, to which he belonged at the time of his dedication, was stationed at Carnuntum on three occasions: from 9 to 62; then from 71 to 86, after having followed Corbulon in Armenia and participated in the war in Judea, a period during which Sacidius may have been involved; finally from 105 to 113, after having fought in Dacia, and before leaving Pannonia for good. The rasura
that covers the last three lines of the text has removed either the name of Nero or, more probably, that of Domitian if one accepts the Syrian origin of the dedicator and his probable entry into the legion in the 60s. If this reasoning is correct, the inscription should be dated to the beginning of Domitian's reign, between 81 and 86, and would be contemporary with Stace's [Thebaid, which also mentions Mithras in a Roman context for the first known time.]
—Bricault; Roy (2021) Les Cultes de Mithra dans l'Empire romain
Other brothers from Carnuntum
This altar bears the oldest known Latin inscription to the god Mithras, written Mitrhe.
Invicto Mitrhe / C. Sacidius Ba/rbarus [c(enturio)] leg(ionis) / XV Apol[linar(is)] / ex voto ....
To the invincible Mithras, Caius Sacidius Barbarus, centurion of the XV Apollinaris legion, upon a vow.