P. 190.—Ceretic or Coroticus. The only source for the following events is Patrick’s _Letter_ (see below); but the identification of Coroticus, who is the subject of the _Letter_, depends on other considerations which seem quite conclusive. The Table of Contents to Muirchu’s Life describes the section which Muirchu devoted to him as _de conflictu sancti Patricii adversum Coirthech regem Aloo_[351] (p. 271; in Muirchu’s text he is simply described as _cuiusdam regis Britannici_, p. 498). _Aloo_ at once suggests the Rock (_Ail_) of Clyde, Bede’s _Alcluith_ (ciuitas Brettonum munitissima usque hodie quae uocatur Alcluith, _H.E._ i. 1), Adamnan’s _Petra Cloithe_; and this identification agrees with the close association of Patrick’s Coroticus with the Picts and Scots, which shows that he must have ruled in Northern Britain. But the determination of Coroticus as ruling at Alcluith is demonstrated (as has been most clearly shown by Zimmer, _Celtic Church_, p. 54, cp. Skene, _Celtic Scotland_, i. 158, note) by a genealogy of the kings of that place, preserved in a Welsh source. In the last quarter of the sixth century, in the time of Columba, Rodercus, or Rhydderch, reigned at Alcluith (Adamnan, _V. Col._ i. 15: Rodercus filius Tothail qui in petra Cloithe regnavit), and we find him also as Riderch hen (Rhydderch the Old) in the _Historia Brittonum_ (ed. Mommsen, p. 206). Now the pedigree of this Rhydderch is found in a Welsh genealogy (ed. Phillimore, in _Y Cymmrodor_, 9, 173): he was son of Tutagual (cp. Adamnan, _filius Tothail_), who was son of Clinoch, who was son of Dumngnal, who was son of Cinuit, who was son of Ceretic _guletic_. It is evident that Ceretic, from whom Rhydderch was sixth, corresponds chronologically to Coroticus, the contemporary of St. Patrick, reckoning a generation—thirty years—to each king. The identification so completely fits with all the data that we can have no doubt of its truth. Thus Zimmer fixes the date of Ceretic or Coroticus as 420-450 A.D. But it is better to say that the reigns of Ceretic and his son Cinuit probably fell more or less between 420 and 480.