The modern human landscape of Dál Riata differs a great deal from that of the first millennium. Most people today live in settlements far larger than anything known in early times, while some areas, such as Kilmartin and many of the islands, such as Islay and Tiree may well have had as many inhabitants as they do today. Many of the small settlements have now disappeared, so that the countryside is far emptier than was formerly the case, and many areas which were formerly farmed are now abandoned. Even the physical landscape is not entirely as it was: sea-levels have changed, and the combination of erosion and silting will have considerably altered the shape of the coast in some places, while the natural accumulation of peat and man-made changes from peat-cutting has altered inland landscapes.
As was normal at the time, subsistence farming was the occupation of most people. Oats and barley were the main cereal crops. Pastoralism was especially important, and trans-human (the seasonal movement of people with their livestock between fixed summer and winter pastures) was the practice in many places. Some areas, most notably Islay, were especially fertile, and good grazing would have been available all year round, just as it was in Ireland. Tiree was famed in later times for its oats and barley, while smaller, uninhabited islands were used to keep sheep. The area, until lately, was notable for its inshore fisheries, and for plentiful shellfish, therefore seafood is likely to have been an important part of the diet.
The Senchus fer n-Alban lists three main kin groups in Dál Riata in Scotland, with a fourth being added later