west coast of Scotland in 563. From there missions were carried out to western Argyll and the islands around Mull. Later the influence of Iona would extend to the Hebrides. In the seventh century, St. Aidan went from Iona to found a church at Lindisfarne off the east coast of Northumbria. The influence of Lindisfarne would spread through the kingdom of Northumbria into what is now south-east Scotland. The result was a series of overlapping and informally organised churches. Iona emerged as the most important religious centre, partly as a result of the work of Adomnan, who was abbot there from 679 to 704. Although it is unclear whether the historic Columba did conduct missions outside of a small part of Dál Riata, Adomnan's Life of St. Columba elevated him to become the apostle of North Britain in general. The means and speed by which the Picts converted to Christianity is uncertain. The process may have begun early. Evidence for this includes the fact that St. Patrick, active in the fifth century, referred in a letter to "apostate Picts", indicating that they had previously been Christian, but had abandoned the faith. In addition the poem Y Gododdin, set in the early sixth century and probably written in what is now Scotland, does not remark on the Picts as pagans. Conversion of the Pictish élite seems likely to have run over a considerable period, beginning in the fifth century and not complete until the seventh and conversion of the general population may have stretched into the eighth century. Among the key indicators of Christianisation are cemeteries containing long cists which are generally east-west in orientation. These cemeteries are suspected, or known to be Christian, because of their proximity to a church, or because of Christian inscriptions found in them. They are found for between the end of the Roman era in the early fifth century and the twelfth century. They are concentrated strongly in eastern Scotland south of the River Tay, in the modern East and Borders of Scotland. Most scholars agree that the place-name element eccles-, from the Brythonic word for church, represents evidence of the British church of the Roman and immediate post-Roman period. Most of these in Scotland are located in the south of the country. From the fifth and sixth centuries, inscribed stones indicate Christianity through their dedications and are spread across southern Scotland. The earliest is