Ancient kingdom, northeastern Ireland and western Scotland.
Known from the 5th century AD, it included the northern part of the present County Antrim in Northern Ireland and part of the Inner Hebrides and Argyll in Scotland. Earlier, Argyll had received northern Irish people known as Scoti and had become an Irish (i.e., "Scottish") area. In the late 5th century the rulers of Irish Dalriada expanded into Scottish Dalriada. Irish Dalriada gradually declined, while the Dalriada of the Scottish mainland continued to expand. In the mid-9th century the Picts were brought permanently under Dalriadic rule, and the whole country was thereafter known as Scotland.