The most extensive evidence for early medieval activity at St Davids takes two forms. The first is documentary; the second is provided by stone sculpture. The Welsh annals record eleven raids by various groups on St Davids between 907 and 1091, which reflect its position as a centre of wealth and power by this time, and point to a wide recognition of both its prestige and the likelihood that it housed portable wealth in the form of precious objects and potential hostages. Viking raiders are specified (‘heathens’, ‘pagans’ or by name) in 982, 988, 999 (when Morgenau, bishop of Menevia, was killed by them), 1001, 1022, 1073, 1080 (when bishop Abraham (1078–80) suffered the same fate as Morgenau), 1089, and 1091. These Vikings were principally based in Dublin, though raiders from other Irish ports, as well as the Isle of Man and Western Isles of Scotland, participated at times.

The early medieval sculpture from St Davids and its environs is well known, having been studied by many scholars, including J. Romilly Allen, V.E. Nash-Williams and J.M. Lewis. Most recently, Dr Nancy Edwards's reassessment of this sculpture has illustrated how it sheds interesting light on the different contacts between ‘Dewisland’ and the world beyond, during this period. The earliest surviving sculpture from St Davids belongs to the ninth century, though the environs contain stones which date from the fifth and sixth centuries.