An early ecclesiastical settlement and modern city, Derry is situated on an island in the river Foyle, although the old rivercourse to the west (the Bogside) had become a swamp by the early historic period. Daire means "oak wood"—its oaks were "sacred" throughout its history. The earliest name form was Daire Calgach (the oak wood of Calgach [person unknown]). By the early twelfth century it is called Daire Coluim Cille, named after St. Colum Cille (d. 597), the traditional founder of the church. However, it has been strongly argued by Lacy that its foundation was by a Fiachrach mac Ciarain, either alone or as joint founder with Colum Cille.
The place was mentioned by Adomnan (d. 704) in his "life" of Colum Cille. It had a church, a graveyard, and a harbour. It was a place of refuge. The reference to a scribe in Annals of Ulster 720, Caech Scuili, indicates that it had a scriptorium. It was mainly staffed by the Cenel Conaill, Colum Cille’s own dynasty. Their rivals, the Cenel nEogain, controlled the surrounding area from 789 onward and made Derry their capital during the eleventh and twelfth centuries. Cenel nEogain success against the Vikings prevented it from becoming an international trading town, but by the late twelfth century it had urban characteristics and had become head of the Columban familia. It had at least three churches and a round tower. Famous abbots were Gilla-Meic-Liag (d. 1174) who succeeded St. Malachy as head of the Irish church at Armagh in 1137, and Flaithbertach Ua Brolchain (d. 1175), under whose direction the town was reshaped. Its school produced the lost Book of Derry, and the lost Gospel of Martin. Much of the literature about Colum Cille was produced here during this period as part of the propaganda associating his name with the site. Annals (now incorporated in the Annals of Ulster) were written there in the late twelfth to early thirteenth century, allowing us a glimpse of secular events.
As a result of the church reform of the twelfth century the monastery adopted the rule of Canons Regular of St. Augustine by about 1220. Soon after 1224, a Dominican priory was founded. For political reasons the seat of the Cenel nEogain diocese was at Raith Luraig in Maghera, County Derry, although some bishops may have lived in Derry. However, in 1254 the Tempull Mor became the cathedral of the diocese of Derry, despite opposition from the Cenel Conaill. Each side had an erenagh (lay head of church) family, Mac Lochlainn (Cenel nEogain) and O’Deery (Cenel Conaill), living in Derry until 1609. The archbishop of Armagh, John Colton, made a famous visitation on 10 October, 1397. The Anglo-Normans came to Derry in 1197, but despite the possibility of establishing a planned colonial town at various times during the following centuries, this did not happen, and the town was largely uninfluenced by them. By the mid-sixteenth century the site had become strategically important to the English, who now gained control and built its (still intact) stone walls between 1613 and 1618.
