A kingdom founded by Fergus and his brothers when they led the Scots from Ireland to the northeast coast of Scotland in the 5th century AD, roughly the modern county of Argyll (Argyllshire). It was ruled from the rock fortress of Dunadd, a nucleated fortified citadel dating to around 500. It consists of a dry-stone central stronghold with two outer walled enclosures. In about 843, Kenneth MacAlpin extended his rule over the Picts to lay the foundations of the kingdom of Scotland. Dálriada was important for its Celtic church under St. Columba and for the island of Iona which was a base for the conversion of northern Britain to Christianity. The Dariada introduced the Picts to their version of the Ogham script as well as the Scottish/Gaelic language.