Complex sentence: The Gaelic overkingdom of Dál Riata was on the western coast of modern Scotland with some territory on the northern coasts of Ireland and probably ruled from the fortress of Dunadd now near Kilmartin in Argyll and Bute.
Split into simpler sentences: The Gaelic overkingdom of Dál Riata was on the western coast of modern Scotland, with some territory on the northern coasts of Ireland. It probably ruled from the fortress of Dunadd, now near Kilmartin in Argyll and Bute.