The Vita Teliaui mentions the following kings as Teilo’s contemporaries:
“Teudiric filio teithpall. Idon filio ynyr guent. Gurcant maur. Mailcun. Aircol lauhir. Catgucaun tredicil. Rein.”
The dating for each of the seven kings listed will be considered.
1. Tewdrig ap Teithfall was of gen. -3. However, that name was at times incorrectly ascribed to Tewdrig ap Llywarch of gen. 1. see Tewdrig.
2. The Buchedd Beuno states Iddon ab Ynyr Gwent had dealings with Cadwallon ap Cafan who belonged to gen. 3, see list 1a in Harleian Genealogies. This dating for Iddon is confirmed by the Liber Landavensis which tells us:
“In the time of the aforesaid King Iddon, the Saxons came into his country to plunder, and he with his army pursued them, and in his way came to St. Teilo …”
Bartrum claims the chronology indicated by the LL is imposssible as Teilo was a contemporary of Dewi. However, the Dewi concerned could have been the later individual, see The two bishop Davids.
4. Maelgwn Gwynedd was of gen. 0, see list 1b in Harleian Genealogies.
5. Aergol Lawhir was of gen. -2, see list 2b in Harleian Genealogies.
6. Cadwgon ap Cathen of gen. 4 has a cognomen that takes the form Trydelic in ABT 18 G and Tredylic in ABT 18 H2. As Bartrum noted, his giving land to Teilo is probably a reference to the church of Teilo.
7. It is unclear which Rhain is being spoken of.
There appears to have been two Teilos. The earlier one was a contemporary of Tewdrig, Maelgwn and Aergol. A possible candidate for the earlier Teilo is Eiludd ap Stater of gen. -1 whose name appears in list 2c of Harleian Genealogies. The Vita explains the evolution of his name thus:
“After he grew up in age, virtue, and wisdom, he was called by intelligent persons by the suitable name of Elios; and Elios, in Greek, is interpreted in Latin by Sol, [the Sun;] for his learning shone as the sun, by illustrating the doctrine of the faithful. But illiterate men corruptly pronouncing the termination of the word, it came to pass, in course of time, that he was called not Elios, but Eliud.”
As noted by Wade-Evans:
“Teilo is not said to be of the stock of Cunedda in B.L.D., nor is his name in P.K. This throws doubt on his Cuneddan origin.”
The later Teilo, who was descended from Cunedda, was the son of Ensych, see list 5 in Bonedd y Saint, and belonged to gen. 1, as did Dubricius, see list 10a of Jesus College ms. 20, who he succeeded as bishop of Llandaff. He could have been a contemporary of Iddon and Gwrgan. He was not of the same period as Aergol Lawhir and as noted by Bartrum:
“In the Book of Llandaf persons named Aircot, Aircol appear as witnesses to two charters in the times of bishops Aeddan and Elwystl. But the properties concerned are in the Dore Valley and a different person is probably indicated.”
 Evans, J. G, Rhys, J., 1893, 118.
 Rees, W. J., 1840, 361.
 Evans, J. G, Rhys, J., 1893, 140.
 Bartrum, P.C., 2009, 95.
 Rees, W. J., 1840, 333.
 Arch. Camb. 86, 163, n. 3.
 Bartrum, P.C., 2009, 5.