[2] The vita of Cybi, found in two (Latin) forms written about 1200, is of very doubtful value, but may be right in making him the son of a Cornish noble who was princeps militae, at a court between the Tamar and the Lynher, possibly Gelliwig.

Cybi politely declined the throne and, instead, traveled through his kingdom, preaching to the people and building churches at Duloe, and Tregony.

The local duke, Edelig, son of Glywys, threatened to evict them from his land, but as he approached them he fell from his horse, which died, and he and his men became blind.

Not far from the church is Ffynnon Gybi (English: St Cybi's Well), whose waters have long been believed to hold healing properties.

Rhyd-y-Saint railway station (English: Saints' Ford) on the Red Wharf Bay branch line near Pentraeth, was named so as Cybi and Seiriol are said to have met there.