[4] He is identified as the third Bishop of Armagh, that is after Patrick's heir Benignus and the Annals of Ulster and Innisfallen record his death in the year 481.

[9] Dónall Mac Giolla Easpaig suggests that the saints could refer to one and the same person:[...] both are given as the third bishop of Armagh [...] placename evidence from the Tuam area would tend to corroborate [this] view [...] the evidence suggests that there was a strong Patrician and, consequently, a strong Armagh influence in the Tuam area from the earliest Christian period [...] the fact that Iarlaithe was a bishop like Benignus of Kilbennan and Felartus of Donaghpatrick, would further indicate that Tuam [...] would have predated Brendan of Clonfert by almost a century.

[4]Jarlath appears briefly as a prominent figure in the medieval Irish Lives of Brendan of Clonfert.

One day, when Jarlath was in his old age, Brendan advised his mentor to leave the school and to depart in a newly built chariot until its two hind shafts broke, because there would be the place of his resurrection (esséirge) and that of many after him.

Because Jarlath acknowledged the divinity and superior wisdom of his pupil, saying "take me into thy service for ever and ever", he gladly accepted his advice.

His monastic school is said to have attracted scholars from all parts of Ireland, including such students as Brendan of Ardfert and Colman of Cloyne.

Jarlath is included in the second order of Irish saints, which implies that he must have lived prior to the year 540.

[2] Saint Jarlath's feast day is 6 June, which is the date of the translation of his relics to a church specially built in his honour next to the Cathedral of Tuam.